When it comes to the standard peer pressure issues, such as drugs, sex and alcohol, I can be a very stubborn person. For example, I don’t like the effects of drinking alcohol in substantial volumes, so if someone actively encourages me to do so, I naturally rail against it. I want to do it my way, or the high way, and woe betide anyone that thinks otherwise. I always imagined that was something to do with the environment I was brought up in: being born an only child and astrologically a Leo to boot surely spurred the development of this obstinate personality trait? Now, a study from the University of Colorado Boulder implies that genetic background might also contribute to succumbing (or not) to peer pressure.

Researcher’s examined DNA data from a study launched in the USA in 1994, Add Health, that tracked American teenagers from grades 7-12 (ages 12-18) onwards. They divided teenagers into those who attended schools that reported either low or high rates of substance abuse and analysed the promoter region that drives expression of the 5-HTT gene, whose function is to regulate the neurotransmitter, serotonin. The 5-HTT promoter comes in three variants: long/long, long/short and short/short, depending on which version you inherit from your mother and your father. The long/long promoter generates higher levels of 5-HTT, which leads to less serotonin, while the short/short promoter does the exact opposite. Individuals with the long/short promoter fall somewhere in the middle.

As you might expect, in school’s with a high rate of substance abuse (where cigarettes and alcohol were more available), greater numbers of pupils were generally involved with these activities, and the converse was also true. But teenager’s who had two ‘long’ copies (long/long) of the 5-HTT promoter had lower-than-average rates of substance abuse, regardless of what their school environment was like.

The 5-HTT promoter has previously been implicated in a variety of mood and developmental disorders: having two long copies (long/long) appears to be protective against the development of depression, while having two short copies (short/short) has been linked to the development of both attention deficit disorder and epilepsy.

Read more about 5-HTT and genetic variability here.