New researcher out from Florida State University shows that teenagers who are living with one biological and one step-parent have lower grades and significantly greater behavioral problems than adolescents from intact families. Further, the study suggests that these problems increase over time. Kathryn Tillman and co-investigators studied data on 11,000 adolescents for this new study, published in the journal Social Science Research.

The authors found heightened negative effects for boys living with half-siblings or step-siblings on behavioral measures and concluded that teens who live with both half-siblings and step-siblings than those who live with one or the other.

Reuters reports:
“‘These findings imply that family formation patterns that bring together children who have different sets of biological parents may not be in the best interests of the children involved,’ said Kathryn Harker Tillman, a professor of sociology at the university.”

“‘…One half of all American step-families include children from previous relationships of both partners, and the majority of parents in step-families go on to have additional children together,’ she added in a statement.”