Mendle and her colleagues looked at more than 1,000 cousins aged 14 and older who took part in the National Longitudinal Survey of Youth.
The more genes the children shared, the more similar their ages at first intercourse — regardless of whether or not the children had an absent father, the study authors found.
This finding, the researchers explained, suggests that environmental factors, such as childhood stress caused by having a single parent or watching their mom date, are not the only ones that carry an influence. Instead, genetic influence also can help explain the tie between absent fathers and early sex.
“While there’s clearly no such thing as a ‘father absence gene,’ there are genetic contributions to traits in both moms and dads that increase the likelihood of earlier sexual behavior in their children. These include impulsivity, substance use and abuse, argumentativeness and sensation-seeking,” Mendle said in the news release.
“The same genetic factors that influence when children first have intercourse also affect the likelihood of their growing up in a home without a dad,” Mendle added.