Not Exactly Rocket Science has a great <a href="http://scienceblogs.com/notrocketscience/2008/09/of_voles_and_men_exploring_the_genetics_of_commitment.php
“>article on the recent finding that the AVPR1A gene is linked to relationship problems in heterosexual men.
Unfortunately, it’s been widely reported in the mainstream media as being a ‘gene for relationship problems’ or a ‘gene for marital bliss’ but it’s really not.
In this case, the gene codes for the receptor of vasopressin, a hormone thought to play a role in bonding in some mammals, but it’s still a long way from the gene to the behaviour.
The media reporting of genetics studies often makes the common mistake of explaining these sorts of findings as ‘a gene for…’ – misdescribing the gene as being specifically for a high-level behaviour and implying a sort of mysterious Gene Genie that magically allows this tiny part of a molecule to influence our lives.
However, these studies only report a statistical association and usually do not tell us about how the gene is linked to behaviour.
This is nicely illustrated in a number of studies that have linked genes to some really quite surprising things.
One of my favourite studies has found that the gene hTAS2R16 is reliably associated with alcoholism. It would be easy to explain this as “a gene for alcoholism” but we know exactly what it codes for: a bitterness receptor on the tongue.
One hypothesis is that people with this version of the gene are less sensitive to bitter things, so they find drinks such as beer more enjoyable, so they tend to drink more, are exposed to more alcohol and so have a higher chance of becoming alcoholic.
From tongue to addiction through the fog of everyday life – maybe. We need to do further studies to test this out and you can see how complex it could get.
Even more counter-intuitive is evidence from a twin study that ‘life events’ are heritable. ‘Life events’ are what psychologists euphemistically called stressful or traumatic things that can happen to us – death of loved-ones, loss of employment, serious injuries. Essentially, they’re the shit in ‘shit happens’.
Unlike molecular genetic studies, twin studies can’t tell us which genes are involved, they just roughly estimate how much of a risk is to do with genetic vs environmental effects, and it turns out that life events are partly inherited.
In other words, we can inherit the chance of ‘shit happening’ from our parents. But in this case, it’s how we explain the ‘happens’ in ‘shit happens’ that matters.
A further study found the risk seems to be related to anxiety and depression so maybe that people with a higher chance of emotional stress might make worse choices in some instances, or maybe more likely to be fired, or keep a relationship going, or maybe have relatives with poorer health (both depression and anxiety are related to physical health problems).
Again, this is a clue, but actually working out a sound scientific explanation that covers the influence of genetics on life events is a massive task.
In other words, genetics studies don’t tell us how the link works, they just tell us it exists, and we need to be careful not to invoke the Gene Genie in our explanation before we’ve done further studies that actually explain the mechanism.