Teens With Half-Siblings More Likely to Use Drugs and Have Sex by Age 15

Having half-siblings increases the chance that a teenager will use drugs and have sex by age 15, according to a study presented at the American Sociological Association annual meeting.

Researchers found that teens who have a half-sibling with a different father are about 65 percent more likely to have used drugs by age 15. They are also about two-and-a-half times more likely to have had sex by that age, HealthDay reports.

“For children, [multi-partnered fertility] means having a half-sibling, but it also means, for first-born children, that they usually experienced their biological parents splitting up — if they were together at all, lived in a single mother household for some time, experienced their mother finding a new partner at least once and perhaps lived with a stepfather, and finally experienced their mother having a baby with a new partner,” researcher Karen Benjamin Guzzo of Bowling Green State University explained in a news release.