Influence of Genetic Dispositions on Sexual Behaviors in Young Adulthood

According to a study published in Health Psychology, genetic influences have a moderate effect on sexual behaviors in young adults.

The study was conducted by Brian Mustanski, Richard J. Viken, Jakko Kaprio, Torsten Winter, and Richard J. Rose. It was published in 2007.

The results are based on a longitudinal study of 4,925 monozygotic and dizygotic Finnish twins.

Since monozygotic twins share all of their genes in common while dizygotic twins share only half of their genes in common, analyzing the differences between both types of twins allowed Mustanski and his colleagues to estimate the genetic influence on sexual behaviors.

Mustanski and his colleagues also investigated the influence of the twins’ shared environment, such as the socio-economic status of their parents, their household and their community. They also investigated the twins’ non-shared environment, which are experiences unique to each individual such as their peers.

They found that for age of first sexual intercourse and number of subsequent sexual partners, “about equal contributions from genetic and non-shared environmental influences explain individual differences, with no evidence of significant effects from shared environment.”

In other words, it appears that genetic dispositions and individual differences in environment, such as one’s group of friends, best predicts the age of first sexual intercourse and number of sexual partners. The environment shared by both twins, on the other hand, did not appear to have any influence.

Man and Woman“But to interpret this evidence of genetic effects on sexual behavior, we must consider the multiple mechanisms that might link genes to behavior, for those mechanism are likely indirect,” notes Mustanski and his colleagues.

It is very unlikely there is a specific gene for sexual behavior, but the effects that genes have on hormones, personality traits, and physical attractiveness probably account for the genetic influence.

As Mustanski and his colleagues explain, their finding has implications for sexual education and promoting sexual health.

“Our evidence of genetic influences on sexual health behaviors suggests that an individual differences approach constitutes a theoretically useful framework to help explain why some individuals are more likely to take sexual risks than others and why some are more resistant to health promotion messages.”


Mustanski, B., Viken, R.J., Kaprio, J., Winter, T. & Rose, R.J. (2007). Sexual behavior in young adulthood: a population-based twin study. Health Psychology, Vol 26, No 5: 610-617.