For a new study published in the journal Nature Genetics, researchers first looked at the genes of more than 120,000 people ages 40 to 69 enrolled in the U.K.’s BioBank program and compared them to the age at which people said they lost their virginity. They identified 38 DNA segments that seemed to affect that number, some of which were related to reproductive biology (as in, linked to the release of sex hormones or age of puberty) and others were associated with appearance and personality.
Next, they repeated the analysis in a group of 260,000 people from the United States and Iceland to verify their findings. We know you’re wondering: The median age for first smash was 18, and though “median” is different from “average,” it’s close.
They found that people who lost their virginity earlier than that were also more likely to have gone into puberty early and have a variant of a gene (CADM2) that’s linked to risk-taking behavior and having more children. People who had sex later than most were more likely to have a variant of the gene MSRA that’s associated with — no joke — irritability. Women, but not men, with red hair and freckles seemed to lose their virginity later than non-gingers.
But ultimately, the researchers said our genes only account for about a quarter of the variation in the age of “sexual debut,” as one epidemiologist called it. The rest can be chalked up to your upbringing and cultural factors (e.g. religious beliefs and peer pressure) and, of course, personal choice. And, no, they’re not studying this out of pure curiosity: Previous research has linked having sex at a younger age to having children earlier, doing worse in school, and having poorer health overall.