Heritable, Non-Genetic Behavioral Patterns

Why do abused children grow up to be abusive parents? Why do people raised in lower socio-economic environments tend to have more long-term health problems? Why is it so hard for drug addicts to kick their habit?

For possible answers, behavioral neuroscientists are turning to a hot new field called behavioral epigenetics. Behavioral epigenetics is the study of inherited changes in behavior or gene expression that are caused by factors other than changes in DNA, i.e., that are epi- (Greek: over, above) genetics.

According to epigenetics theory, environmental factors such as the degree of nurturing (or lack of it) by one’s parents early in life can alter the chemical structure of DNA (specifically, the degree of methylation of DNA and its associated histones). This in turn affects how and when certain genes are turned on and off. In theory, such chemical alterations in DNA could last for multiple generations (i.e., be heritable) even though the nucleotide sequence of the genes themselves hasn’t changed.

So far, there’s very little evidence to suggest that epigenetic mechanisms influence human behavior, mostly because human brain tissue is not readily available for research. However, laboratory studies show that rats raised by less-nurturing mothers tend to be more prone to stress as adults and to exhibit increased methylation of certain genes. It’s worth keeping an eye on this developing field to see where it leads.