Category: Theory

A hazy memory of the happiness disorder

The ex-chief executive of the British Medical Journal has an amusing blog post where he notes how a Phillip Roth novel Sabbath’s Theater brilliantly ‘mimics’ a BMJ Group article on how happiness is a disease, seemingly unaware that his journal genuinely published the article in question.

At one point in the book Mickey is visiting his alcoholic wife in a clinic and after betting on the blood pressure of various patients he encounters a young woman with “a scar on her wrist” who has been in the library of the clinic reading medical journals. She reports “word for word” on what she has read in the Journal of Medical Ethics.

I was stopped short when I read this—because the Journal of Medical Ethics is published by the BMJ Group, and I was responsible for it when I was the chief executive of the group. For a moment I wondered if the piece was really from the Journal of Medical Ethics…

Roth mimics well the stilted prose of medical journals with their heavy emphasis on the passive voice. He also mimics the science that leads to problems becoming diseases. The “relevant literature” has been reviewed. This made me think immediately of Stephen Lock, my predecessor as editor of the BMJ, who always struck out “medical literature” and substituted “published reports.” “This stuff is not literature” he used to protest.

In fact, the article was genuinely published in the Journal of Medical Ethics and is titled ‘A proposal to classify happiness as a psychiatric disorder’.

It was written by British psychologist Richard Bentall who, although was clearly having some fun, was also making a serious point about the criteria we use to define mental illness.

Bentall is a long-time psychosis researcher and at the time it was not widely acknowledged that it was possible to have experiences common in diagnoses like schizophrenia, such as hearing voices, without any distress or impairment.

This is why he focuses on the statistical abnormality of the happiness state, its possible neurobiological underpinnings and it cognitive effects, often (over)used to justify why a condition is a ‘real disorder’, and then finishes with “One possible objection to this proposal remains – that happiness is not negatively valued. However, this objection is dismissed as scientifically irrelevant.”

At the time, the satire was widely missed by the British press who ran lots of ‘barmy boffin’ type stories with headlines lines like “Top Doc Talks Through Hat”.

Despite its history of being misunderstood and misremembered, it remains a cutting critique of psychiatric classification and is well worth a read.
 

Link to blog post on Roth’s novel.
Link to full text of article (click PDF link) on happiness as mental disorder.

Drug classification is out of order

Mark Easton’s BBC News blog tackles a recent study that has ranked the dangers of numerous recreational drugs – citing alcohol as the most hazardous to health ahead of even heroin and cocaine.

The study, just published in The Lancet, is interesting not just because it is yet another that shows the disconnect between official policy and the actual evidence on drug harm, but because the authors are some of the people who were sacked or resigned after the UK government got upset that they kept highlighting inconvenient evidence to this effect.

Its worth noting that ranking drug harms is an inexact science. For example, injecting any drug regularly massively increases the health risks, so opinion varies on whether you should count this is as a danger attached to a specific substance – when some drugs – like heroin, can be taken with or without injecting.

Regardless of the exact ranking, the general pattern found in this any many other studies highlights the ongoing reluctance to deal with drugs as they actually affect society.

Mark Easton’s BBC News blog is consistently excellent by the way, and a genuinely incisive attempt to get at the real evidence behind many pressing social issues.
 

Link to Mark Easton on ‘Drug Debate Hots Up’.
Link to paywalled Lancet study.

A consciousness raising exercise

I’ve just discovered the fantastic Conscious Entities blog that is full of wonderfully insightful discussions about the science and philosophy of consciousness.

As well as covering established theories it also tackles new ideas and controversies as they appear, with the fantastic coverage of philosopher Peter Hacker’s criticisms of just about everything in neuroscience and the subsequent backlash being a case in point.

Despite dealing with heavyweight issues, it’s also quite playful and I loved this explanation in the About page:

One possible source of confusion is that some of the discussions here are presented as dialogues between two different characters. One of these, whom I think of as ‘Blandula’, after the Emperor Hadrian’s verse addressed to his own soul, is represented by a sort of cherub, and is suspicious of reductive and materialist ideas: the other, (‘Bitbucket’, represented by an abacus) takes the opposite view. I hope this helps both sides to benefit from vigorous advocacy, but the two characters are merely figments of my imagination and I cannot supply email addresses for either of them.

Fun, smart, informative and, as far as I can make out, illustrated by the author.
 

Link to Conscious Entities (via @AlexKaula).

What price sobriety (in vouchers)?

BBC Radio 4 recently ran a fascinating one-off programme called Sugaring the Pill on schemes that pay people to lose weight, get vaccinated or stay off drugs. Payment turns out to be particularly effective at keeping addicts clean and this caught my eye because it seems to go against some of the core scientific beliefs about persistent drug users.

The programme explores the ethics of payment programmes and the public’s discomfort, particularly when applied to drugs, with handing out rewards for something we should perhaps be doing anyway.

Payment as treatment is known in the medical literature as ‘contingency management’ and has been found to be most effective in keeping heroin and cocaine addicts clean.

As the programme, and the research summary linked above, describe, a typical payment scheme will give a ticket for every clean urine test – usually starting with a small value like £1, and increasing by 50p each time.

Only when the patient has completed a whole series of clean drug tests, maybe after a month or two, can they exchange their tickets for shopping vouchers which they can spend in the high street.

The fact that these schemes are so effective is surprising, because they rely on abilities thought to be lacking or impaired in addicts – mainly the capacity to delay rewards and gratification.

There is now a host of research showing that addicts have problems with temporal discounting. We all have the tendency to judge future benefits as significantly less important than immediate ones but this seems to be enhanced in drug users who greatly overly prioritise rewards that arrive sooner.

Also, persistent drug use is widely believed to alter the brain’s reward system so positive reinforcement (wanting benefits) becomes less persuasive than negative reinforcement (the desire to escape an unpleasant sensation).

Similarly, research suggests that in addiction, the desire to take drugs become less modifiable by our executive system and so less amenable to voluntary control.

So, for people who should be primarily motivated by immediate chemical rewards over long-term abstract benefits, a slowly accumulating shopping voucher scheme would be the last thing you would predict to have such a reliable effect on keeping people off the smack or blow.

I note this purely as a curious inconsistency and if you have any suggestions that might explain it, do add them in the comments.

The BBC programme is excellent, by the way, and is also available as a podcast.
 

Link to Sugaring the Pill info and streamed version.
Link to page with podcast (for four weeks).

It only exists if I can see colours on a brain scan

Bad Science has an excellent piece on the recent hot air from a researcher who claimed that brain activity differences between people with high and low sex drive proved that ‘hypoactive sexual desire disorder’ was ‘a genuine physiological disorder and not made up.’

This strikes me as an unusual world view. All mental states have physical correlates, if you believe that the physical activity of the brain is what underlies our sensations, beliefs and experiences: so while different mental states will be associated with different physical states, that doesn’t tell you which caused which. If I do not have the horn, you may well fail to see any increased activity in the part of my brain that lights up when I do have the horn. That doesn’t tell you why I don’t have the horn: maybe I’ve got a lot on my plate, maybe I have a physical problem in my brain, maybe I was raped last year. There could be any number of reasons.

But far stranger is the idea that a subjective experience must be shown to have a measurable physical correlate in the brain before we can agree that the subjective experience is real, even for matters that are plainly experiential. If someone is complaining of persistent low sex drive, then they have persistent low sex drive, and even if you could find no physical correlate in the brain whatsoever, that wouldn’t matter, they do still have low sex drive.

One of the reasons why attempts to make problems of behaviour or experience seem ‘biological’ is that the concept is strongly linked to the idea that if something is a ‘biological disorder’ we are less to blame because we have less control over the symptoms.

This is daft, of course, because although biology uses less talk of free will and agency, it is really just another level of explanation.

The beauty of a captivating picture doesn’t somehow disappear if we discuss the molecules of the paint and, in a similar way, discussing the interactions of neurons won’t mean that the problem of free will no longer applies.

But the drive to try and eliminate free will is, in part, because of the stigma still attached to many types of problems. Instead of trying to tackle stigma we often try to misguidedly reclassify the object of the stigma.

It’s like trying to fight racism by classifying a wider range of skin colours as white – it really misses the point and actually maintains the prejudice. In the same way, we should be working towards accepting all human difficulties, however they are most appropriately described by scientific theories, as valid and worthy of concern.

This does not mean all necessarily need to be classified and treated as medical disorders, but it does mean that we should respect the difficulties people face and think about constructive ways of helping ourselves and other people to tackle them.
 

Link to Bad Science on ‘Neuro-realism’.

The outer limits of psychiatric genetics

The Wiring the Brain blog has a fantastic piece on the how whole genome sequencing is already showing us the limits of how we understand the genetics of mental illness.

Whole genome sequencing allows the entire length of someone’s DNA to be read and, when data from enough people has been collected, it’s possible to look for reliable links between genetic information and human traits.

The advantage of this technique is that it allows genetic links to be detected without needing a specific idea about what should link with what beforehand.

It’s often been cited as the ‘new hope’ for psychiatric genetics which attempts to understand the genetics of mental illness.

However, one difficulty with looking for genetic links with mental illness is that people diagnosed with conditions like schizophrenia or bipolar are unlikely to have exactly the same thing while the specific components are not perfectly measurable (there is no cut and dry way of classifying intrusive thoughts for example).

In addition, most genetic studies to date have found that changes in single genes can explain only a tiny fraction of the risk of developing a mental illness and are often present, although less frequently, in healthy people.

Owing to the fact that the heritability of mental illness can be quite high, the current thinking is that the risk is likely transmitted through lots of genes that, although individually have a small effect, can greatly increase the risk if transmitted together.

The Wiring the Brain post does a brilliant job of exploring why picking out these genes and genetic patterns may not just be a problem with not having enough data – but with the techniques themselves.

However, we will still likely be left with a situation where the statistical evidence we can get from considering the spectrum of mutations in single genes will run into mathematical limits. At some point it will be necessary to look for other types of evidence from outside the system. One type of evidence will come from analysing the biochemical pathways of the implicated genes – it is already becoming apparent that many such genes encode proteins that interact with each other…

The point about mathematical limits is an interesting one, as it may be that there are genes or genetic patterns which are important but have such a small effect that you would need a sample size so big (millions and millions of people perhaps) that your study would simply be impossible.

As the post indicates, this may kill the idea that the genetics of mental illness can be studied without any existing theories and just by looking at which links turn up.

It’s a bit like trying to work out how riots start by counting the different types of people in crowds and seeing which types of people are more likely to be present when a fight breaks out.

Without knowing about the roles of different people, you could easily conclude that the police are the ones responsible for the riot because they are always there in big numbers, while the firebrand orator demanding death to the government is irrelevant because there’s only one of him.

The Wiring the Brain piece covers this and several other issues and is one of the most interesting articles on psychiatric genetics I have read in a while. The blog, by the way, is consistently excellent, so definitely one to keep tabs on.
 

Link to Wiring the Brain on ‘Searching for a needle in a needle-stack’.

Susto: a soul wrenching fright

Neuroanthropologist Daniel Lende alerted me to this short video of an Ecuadorian healer or curandera treating a condition called ‘susto‘.

‘Susto’ literally means ‘fright’ in Spanish but the patient is not simply assumed to be suffering from shock or anxiety as the fright is thought to have caused the soul to leave the body which, in turn, causes a range of psychological and physical symptoms.

The anthropologist Arthur Rubel, who was one of the first to study the condition in detail, examined a range of cases and drew up a short list of its symptoms that included: “(1) during sleep the patient evidences restlessness; (2) during waking hours patients are characterized by listlessness, loss of appetite, disinterest in dress and personal hygiene, loss of strength, depression, and introversion”.

However, as an influential study by Michel Tousignant noted that other anthropologists have given remarkably different definitions, including fever, muscular pains, complexion changes, nausea, vertigo, and stomach or intestinal upsets; the inability to carry out your normal social role; an emotional crisis related to love or sexual problems, or, in the highlands of Ecuador, a problem that normally effects children that can lead to death if unchecked.

This last definition seems to be exactly what is being treated in the video as in the last few frames you can see a whole row of children being attended by curanderos and the video is labelled as taken in the highland Ecuadorian city of Cuenca.

The American Psychiatric Association’s DSM defines ‘susto’ as a culture-bound syndrome which is supposed to be a non-universal syndrome which only occurs in a specific culture but actually means a syndrome that only appears in foreign cultures as the category seems to automatically exclude a diagnosis if it appears in Americans.

Although its tempting to classify the condition as a form of mental illness, Tousignant’s work makes clear that this is misguided as the condition is defined as primarily spiritual in nature with what we would call ‘symptoms’ being knock-on effects.

It would like be a bit like trying to define poverty as a mental illness. While you can see that it causes mental stress, defining it as a psychiatric disorder doesn’t make much sense because it is best understood as an economic concept.

The same applies to ‘susto’. You cannot define it as a mental illness, as the DSM tries, without stripping it of its meaning from the cultures in which it appears.
 

Link to YouTube video of curandera treating ‘susto’.

A nasty case of misery

BBC Radio 4 has a short but excellent programme on the increasing medicalisation of human sadness which notes that even everyday talk about difficult but necessary life events is being increasingly couched in medical terms.

The writer and presenter of the piece, journalist Mary Kenny, notes, for example, how the concept of trauma is being increasingly applied to mourning, previously considered a painful but normal response to tragic circumstances. She also tackles how this tendency is being reflecting in the ongoing widening of the criteria for mental illness.

Kenny’s piece neither relies on tired simplifications of ‘evil drug companies’ nor falls back on simple explanations for mental illness and makes for a insightful short analysis of how our understanding of human distress is changing.

Unfortunately, you can only listen to a streamed version of the piece and it will disappear in four days, so catch it while you can.
 

Link to ‘Medicalising Melancholy’ on BBC Radio 4.
Link to article on BBC News website based on the programme.

The taste of the past

The latest edition of The Psychologist has a fascinating article on ‘sensory history’ – the practice of investigating how people from the past differently interpreted and understood sensory experiences.

I was first alerted to the idea by a book review we covered back in 2009 which noted that the superstition of the ‘evil eye’ – where you can curse someone by looking at them – makes more sense when you realise people believed that the eyes actively emitted rays rather than passively receiving them.

This new article is by sensory historian Mark Smith, author of the book Sensing the Past, who examines how the meaning of the senses has changed over time.

This part particularly caught my eye (pun intended) as it describes how the print revolution made the sense of sight seem more ‘truthful’ and ‘objective’:

In part, at least, historians of the sensate attend to the nonvisual senses principally because we have, for so long, assumed the supremacy of the eye in the human sensorium. Historical interest in smell, sound, touch and taste has been animated often because of the assumed ascendancy of vision that emerged following the print revolution and the developments of the Enlightenment, many of which supposedly elevated the eye as the arbiter of truth, the producer of perspective and balance (courtesy of the invention and subsequent dissemination of visual technologies such as the telescope, microscope and camera) and, in the process, diluted the value placed on the nonvisual, often proximate senses of hearing, olfaction, tasting, and touching.

It seems – or, at least, some sensory historians now theorise – that this supposed revolution in the senses was so thoroughgoing that moderns –at least those of the Western 18th-, 19th- and 20th-century variety – increasingly dismissed the other senses as reliable indicators of reason and truth and, instead, came to associate them with emotionalism or, more often than not, hardly worthy of sustained scholarly investigation.

 

Link to ‘The explosion of sensory history’.
 

Full disclosure: I’m an unpaid associate editor and occasional columnist for The Psychologist who has trouble sensing breakfast, let alone history.

Inattention to details

Neuroskeptic has excellent coverage of the recent headline-making study on the genetics of ADHD that was overly-hyped as the ‘first direct genetic link’ to the disorder and overly-slammed as a drug company ploy.

For example, BBC News has a report on the study where you can see researcher Anita Thapar making some unrealistic claims for the significance of the interesting-but-preliminary study while the science-retardant child psychologist Oliver James counters by cherry picking evidence (and not even very accurately).

Neuroskeptic does a great job of untangling the actual import of the research and discusses why the finding of copy-number variations or CNVs in about 16% of the ADHD kids compared to 7.5% of the controls is neither a ‘direct genetic link’ nor evidence against the idea that the condition is ‘socially constructed’.

However, I was particularly drawn by Thapar’s comments that discovering the genetic component “should address the issue of stigma.”

The common idea is that if we can demonstrate a particular mental disorder is a ‘brain disease’ or the result of a biological dysfunction people who have the condition will be less stigmatised due to a vague notion that their behaviour ‘is not their fault’.

Unfortunately, studies to date have shown that biological explanations for mental disorder actually increase stigma in public, patients and mental health professionals because the affected people are typically seen as more unpredictable and dangerous than when social or psychological explanations are given.

It is genuinely important that we understand the genetic influences to behavioural problems, including those that get classified as ADHD, and this new study is a small but important step toward that aim.

But we kid ourselves if we think this evidence automatically decreases stigma and we do society a disservice if we make our acceptance and compassion for people with behavioural difficulties dependent on certain types of scientific explanation.
 

Link to excellent Neuroskeptic piece on genetics and ADHD study.

Cultures of friendship

Neuroanthropology has an all-too-brief interview on how different cultures around the world have fundamentally different ideas about what it means to be a friend.

The interviewee is anthropologist Dan Hruschka who has just written a book summarising his research on the anthropology of friendship.

It’s a wonderfully simple idea but really challenges some of our core assumptions about social relationships:

Can you describe one of your examples that really makes us think differently about friendship?

When you look at friendship cross-culturally, there are many surprises! Consider the fact that in societies around the world, close friends will sanctify their relationships with elaborate public ceremonies not unlike American weddings or that parents or elders can arrange their children’s friendships in much the same way that marriages are arranged in many parts of the world.

I think one of the more interesting findings, and one that reveals our own American preferences and taboos, concerns the kinds of things that friends are expected to help each other with. For example, in the U.S., we often expect friends to talk through personal problems and disclose deep secrets. Indeed, U.S. researchers often impose this criterion on definitions of friendship.

However, there are many places in the world where such verbal, emotional support is only a minor concern in friendships.

 

Link to Neuroanthropology on ‘the book of friendship’.

Online therapy: a download off your mind

What’s it like doing psychotherapy in Second Life? New Scientist has a level-headed article that describes how personal therapeutic interactions are altered by the online world and how this may be a benefit for people with certain types of problems.

In my limited experience of Second Life, I was struck by how many people were offering commercial counselling services, many without apparent qualifications, and I’ve seen been a bit sceptical since.

The NewSci piece is by a professional counsellor and takes a critical look at the concept and its practice, relating both the experience of therapy and where its strengths and weaknesses lie, not least for people who may have social anxiety or other face-to-face difficulties.

The other major concern is the loss of body language. For people used to Second Life, this is not as much of a problem as you might think, according to Dillon. But as a therapist, I glean a great deal from seeing someone become tearful or shift in their seat.

It’s a trade-off, say avatar therapists. What you lose in body language you gain in the eloquent expression of conscious thought – at least for clients who type in their responses – as well as the loss of inhibition that comes with communicating through an avatar.

I have to say, having read so much drivel about ‘cyber therapy’ I was ready to dismiss the article but found it one of the best introductory pieces I’ve yet read that tackles online psychotherapy.
 

Link to NewSci on Avatar therapy.

Watch the skies

The BBC World Service has an excellent documentary that visits the SETI Institute, a project that is scanning for skies for signs of extraterrestrial intelligence.

The occasion is the 50th anniversary of the Drake equation, a mathematical formula that attempts to estimate the number of alien civilisations that exist in the universe.

On one hand, it’s quite charming (admittedly, in a slightly patronising way) to think of scientists earnestly looking for aliens from outer space, but on the other, it’s an interesting psychological problem that involves a guess about what other forms of intelligence might be like.

As artificial intelligence researchers will tell you, we tend to increasingly define intelligence to mean exactly and only what humans can do. When machines manage to equal a human cognitive ability, by playing chess for example, we just move the goal posts and suggest ‘real intelligence’ is whatever the computer can’t do yet – something called the AI effect.

The fact that the SETI project is looking for other ‘civilisations’ itself relies on assumptions that civilisation is a common result of intelligence. This raises the question of whether we would recognise alien intelligence if we met it. And perhaps, more importantly, would it recognise it in us?

The BBC documentary is an engaging look at the motivations and assumptions behind the SETI project as well as how they are implemented in the day-to-day running of the search.

However, because the BBC has yet to fully come to grips with intraterrestrial intelligence, the programme stream and podcast will disappear in a few weeks, so be quick.
 

Link to documentary on SETI and alien intelligence.

Towards an operating system for brain hacking

Electronic devices that interface directly with the brain are now being produced by labs around the world but each new device tends to work in a completely different way. An article in Technology Review argues that we need an agreed neural operating system so brain-machine interfaces can more easily work together.

Although current devices tend only to measure brain activity or stimulate cortical areas, it won’t be very long before devices typically do both – detecting and reacting to neural states – possibly forming a dynamic network of electronic devices that regulate brain activity.

To avoid the ‘Mac vs PC problem of the brain’, neuroscientist Ed Boyden highlights the importance of having devices that speak a common language to avoid both wasted scientific effort and potentially dangerous miscommunication.

Some examples of this kind of “brain coprocessor” technology are under active development, such as systems that perturb the epileptic brain when a seizure is electrically observed, and prosthetics for amputees that record nerves to control artificial limbs and stimulate nerves to provide sensory feedback. Looking down the line, such system architectures might be capable of very advanced functions–providing just-in-time information to the brain of a patient with dementia to augment cognition, or sculpting the risk-taking profile of an addiction patient in the presence of stimuli that prompt cravings.

Given the ever-increasing number of brain readout and control technologies available, a generalized brain coprocessor architecture could be enabled by defining common interfaces governing how component technologies talk to one another, as well as an “operating system” that defines how the overall system works as a unified whole–analogous to the way personal computers govern the interaction of their component hard drives, memories, processors, and displays.

Although not mentioned in the article, another advantage of a common platform for brain devices would be security, as current devices as often completely open and designed to be easily controllable from the outside.
 

Link to TechReview article on ‘Brain Coprocessors’.

Dreams of a consciousness measuring device

The New York Times has an excellent article about Giulio Tononi, one of the few neuroscientists trying to understand consciousness in a way that may have a direct practical application – to create a medical device that can tell whether you are conscious or not.

To be honest, I’ve been a bit bored with consciousness, not in an existential sense you understand, but in terms of the science which tends towards tinkering with interesting but possibly inconsequential effects.

The NYT article, however, is completely riveting, as it discusses Tononi’s quest to understand consciousness to the point of building a ‘consciousness meter’.

Although it may sounds fanciful, it could have an important medical application – to help anaesthetists determine when a patient is actually aware of what’s happening to them.

If you’re not familiar with surgery you’d think this was easy enough to determine except for the fact that muscle relaxant drugs are often administered.

This means that even if you’re awake, you can’t communicate the fact, occasionally leading to terrifying cases of people who are conscious but paralysed while operated on.

So ideally, anaesthetists would like a machine that gives a consciousness ‘read out’ from the brain. There is something called the bispectral index, which claims to measure depth of anesthesia, although it turns out not to be a very good guide to consciousness.

Of course, to create a device to measure consciousness, we need to understand its neuroscience, and Tononi has a unique theory he is working on:

Consciousness, Dr. Tononi says, is nothing more than integrated information. Information theorists measure the amount of information in a computer file or a cellphone call in bits, and Dr. Tononi argues that we could, in theory, measure consciousness in bits as well. When we are wide awake, our consciousness contains more bits than when we are asleep.

For the past decade, Dr. Tononi and his colleagues have been expanding traditional information theory in order to analyze integrated information. It is possible, they have shown, to calculate how much integrated information there is in a network. Dr. Tononi has dubbed this quantity phi, and he has studied it in simple networks made up of just a few interconnected parts. How the parts of a network are wired together has a big effect on phi. If a network is made up of isolated parts, phi is low, because the parts cannot share information…

Dr. Tononi argues that his Integrated Information Theory sidesteps a lot of the problems that previous models of consciousness have faced. It neatly explains, for example, why epileptic seizures cause unconsciousness. A seizure forces many neurons to turn on and off together. Their synchrony reduces the number of possible states the brain can be in, lowering its phi.

The NYT piece is a fantastic look into the ideas behind the theory and the exciting possibilities it presents.
 

Link to NYT on ‘Sizing Up Consciousness by Its Bits’.

Mind gene myths

The Guardian has an excellent article on why news stories touting a gene for a particular psychological trait, like intelligence, optimism or dyslexia, are usually misguided.

The piece is a fantastic potted guide to how science goes about untangling the effects of genes and the environment and how this applies to the increasingly popular attempt to link genetics to personality, thinking and behaviour.

What are the implications of all this for the stories we hear in the media about new genetic discoveries? The main message is that we need to be aware of the small effect of most individual genes on human traits. The idea that we can test for a single gene that causes musical talent, optimism or intelligence is just plain wrong. Even where reliable associations are found, they don’t correspond to the kind of major influences that we learned about in school biology. And we need to realise that twin studies, which consider the total effect of a person’s genetic makeup on a trait, often give very different results from molecular studies of individual genes.

Don’t be put off by the picture of Jedward. Not all twin studies are quite so gruesome.
 

Link to article on myth of ‘a gene for things like intelligence.’