Genetically informed research helps us not to be fooled into believing that a certain experience leads to a certain outcome but to probe whether a genetic predisposition leads to the experience and the outcome.
Take the conventional wisdom that their parents' divorce increases the risk that children will develop depression. "It turns out that the increased risk of depression in these children reflects a common genetic liability in the parents and kids," says Brian D'Onofrio of Indiana University, Bloomington. Since depressed people have more trouble getting and staying married, this genetic risk of depression raises their risk of divorce, he finds in a study submitted for publication. Parents pass that risk of depression to kids through DNA, not a failed marriage.
In cases of divorcing parents, smoking moms and pregnant teens, genetically sophisticated studies show that what was thought to be the causal factor isn't. Instead, something inherent in the children affected by divorce, smoking or pregnancy is at work.
Living with a father who steals, brawls and can't hold a job raises a child's risk of similar behavior. But children also inherit genes from dad. In principle, either the experience or the genes might push them to follow in his antisocial footsteps. The longer a child lives with such a father, the greater the risk of a similar fate. That suggests that keeping families intact is not always in a child's best interest. As Jenae Neiderhiser of George Washington University says, "the strength of genetically informed studies is that they are just as useful for identifying the effects of environment."
Source: The Wall Street Journal, June 16, 2006