depression : nature vs nurture

http://www.sciencedaily.com/releases/2006/10/061012190132.htm

Among children from supportive, nurturing families, those with the short form of the serotonin transporter gene (known as 5-HTTLPR) had a significantly reduced risk for depression, found the UCLA team, under the direction of Shelley E. Taylor, UCLA distinguished professor of psychology and an expert in the field of stress and health. The research team also found that among children from emotionally cold, unsupportive homes marked by conflict and anger, those with the short form of the 5-HTTLPR gene were at greater risk for depression, as some previous research has also shown.

This may explain at least some of the reason for the high rates of depression in the U.S. compared with some other countries, since a large percentage of American families are far from supportive and nurturing.

Of course, nurturing behaviour is not the same as permissiveness.