The first time: Genetic factors in early sexual activity

Looking at the genomes of over 125,000 British men and women, researchers identified 38 genetic variants which were statistically correlated with the age at which people first had sex. Some of the genetic variants identified in the study have previously been linked to timing of puberty and number of children, and to behaviors like risk-taking. The study is published in Nature Genetics.


Dr. Alicia Smith, Associate Professor, Psychiatry and Behavioral Sciences, Emory University (webpage):

Expertise: The role of genetic and environmental factors in the development and symptoms of stress-related disorders across the lifespan.

“This is a hard paper to evaluate.  The methods are not the traditional ones used. Their results suggest that a much larger proportion of the genome is associated with age at first sexual intercourse than one typically sees in genome-wide association studies.  In many cases, this indicates that the statistical model used to test the association doesn’t fit the data and that there are false positives in the results.

“Certainly, the age at which a person first has sex is based on a lot more than the age at which they are first biologically capable.  It is also based on cultural and socioeconomic factors that are very difficult to account for in genetic studies. While this study does find an association with genetic factors, it nonetheless supports the idea that the age at which a man or woman first has sex is overwhelmingly due to non-genetic factors, such as social or environmental context.  Among 40-69 year old adults in the United Kingdom that report their age at first sexual intercourse between 18 and 21 years, the study estimates that genetic factors can account for 1 year, but environmental factors account for the other 3 years.”



Declared interests (see GENeS register of interests policy):

None declared.



Physical and neurobehavioral determinants of reproductive onset and success‘ by Day et al., published in Nature Genetics on Monday, 18 April 2016

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