Kids with half siblings by different dad likelier to have drugs and sex by 15

A new research has claimed that adolescents having half-siblings with a different father are likelier to use drugs and have sex by the time the reach the age 15.

Using data from the National Longitudinal Study of Youth, Karen Benjamin Guzzo, an assistant professor of sociology at Bowling Green State University, and Cassandra Dorius, an assistant professor of human development and family studies at Iowa State University examined a phenomenon known as 'multi-partnered fertility' or MPF. This happens when parents who are not romantically involved with each other form new relationships and have another child with a new partner.

Guzzo said that it's not new behaviour, but it's happening more often as more people are having children outside of marriage.

According to Guzzo, this is the only study that takes into account background factors (like the mother's level of education and household poverty) and the number of changes in family structure the adolescent experienced.

The researchers looked at the connections between this re-partnering and additional childbearing on adolescent drug use and early sex. They focused on mothers and first-born children who lived with their mother most of their lives.

Guzzo said that for kids, MPF 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.

Researchers looked at the mother's educational background, her own family structure growing up, and whether the child experienced bouts of poverty. They also examined family factors - whether the father lived with them at birth, how many family transitions the adolescents experienced, and whether the mother ever married or cohabited, with the child's father or another partner.

Guzzo said that the team found that first-born adolescents with half-siblings with the same mother but a different father do have less favourable outcomes compared to their peers with only full siblings, even after accounting for mom's background characteristics, socioeconomic factors the child experienced growing up, and family instability and structure.

She said that adolescents with a half-sibling with a different father are about 65 percent more likely to have used marijuana, uppers, inhalants, cocaine, crack, hallucinogens, sedatives, or other drugs by the time of their 15th birthday than those who have only full siblings.

She added that these adolescents are also about 2.5 times more likely to have had sex by their 15th birthday than their peers with only full siblings.