A US study has found that children whose mothers have multiple partners and who live with half-siblings have more frequent behavior problems in middle childhood compared to children in family structures that don’t change and where all children have both parents in common.

The researchers, led by Paula Fomby at the University of Michigan, looked at the experience of 3,062 children living most or all of their time with their mothers. The data came from the Fragile Families and Child Wellbeing Study, which follows children born in large US cities between 1998 and 2000.

By the time they reach age 9, nearly one in two children born to unmarried mothers and one in eight children born to married mothers in US cities will experience changes in their mother’s relationship status and will have at least one half-sibling conceived with a partner other than the child’s own biological father.

The researchers looked at the mother’s marital status when her child was born, the number of family relationship changes the child experienced by age 9, and the number of partners with whom mothers reported having other children, either before or after the child’s birth. Then they asked about the child’s behavior problems at age 9 – disobedience as reported by the child, aggression and rule-breaking as reported by the child’s mother, and disruption in the classroom, as reported by the child’s teacher.

The researchers found that children born to unmarried mothers had more frequent behavior problems when they experienced three or more changes in their mother’s relationship status. Prior research has looked separately at whether parents’ prior relationship changes and childbearing with multiple partners is related to children’s behavior, but this work is the first to consider both these frequently simultaneous circumstances.

When they examined the dynamics behind these changes in children’s family composition, they found that mothers who experienced frequent relationship changes also reported greater financial hardship, harsher discipline strategies, and more frequent residential moves. These factors may explain why relationship instability is associated with children’s behavior problems.

The researchers conclude by advising that social programs supporting fragile families should do more to recognize relationship instability and complexity when targeting their help to the most needy children.

Header photo: CK, Carl, Carlo, Carlito. Creative Commons.


Fomby P & Osborne C (2016), Family instability, multipartner fertility and behavior in middle childhood, Journal of Marriage & Family