Research Shows Negative Effects of Half-Siblings

ScienceDaily 11 August 2013
Adolescents who have half-siblings with a different father are more likely to have used drugs and had sex by age 15 than those who have only full siblings. That’s according to new research from 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.

Using data from the National Longitudinal Study of Youth, they 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.

“It’s not new behavior, but it’s happening more often as more people are having children outside of marriage,” said Guzzo.

According to Guzzo, this is one of the first studies to examine the effect of parental MPF on children over the long-term, and the only study that takes into account background factors (such as 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.
http://www.sciencedaily.com/releases/2013/08/130811005336.htm