[Paramutation] describes an interaction between different alleles or even different loci [areas on a chromosome], which results in a stable alteration in their functional state… Consequently, the properties of an inherited gene may in part be dependent on a gene sequence that is not actually co-inherited. Clearly, this flouts what we generally think of as genetic inheritance. Furthermore, if parental experiences affect the expression of RNA molecules involved in RNA induced DNA silencing, it is conceivable that heritable changes in gene activity might result from environmental stimuli.
An excerpt from p21 of Psychiatric Genetics and Genomics (ISBN 0198564864) that describes a potential way that experience could affect the genetic information that gets inherited by the next generation.
This is part of a largely unexplored area known as epigenetics which examines the biochemistry of gene expression.
It is thought that understanding epigenetics will be crucial for working out the genetic influences on mind and brain function.