Before they reach young adulthood, many children in the United States will experience their parents separating, divorcing, finding another partner or getting remarried. 

When families change structure, it is more common for children to exhibit behavior problems, such as aggression and defiance, and a new psychology paper say that behavior problems in children increased in high-income families most, and that children's age also played a part in their likelihood of having behavior problems.

Moving from a single-parent family into a step-parent family then improved children's behavior in higher-income families but not in lower-income families.

"Our findings suggest that family changes affect children's behavior in higher-income families more than children's behavior in lower-income families—for better and for worse," notes lead author Rebecca M. Ryan, assistant professor of psychology at Georgetown University.

The authors used  results culled from a national sample of nearly 4,000 children in the Children of the National Longitudinal Survey of Youth. They sought to examine how different kinds of family changes related to children's behavior problems between ages 3 and 12.

Survey results were divided into three groups: those children in families living under 200% of the federal poverty line (FPL), those living between 200% and 300% of the FPL, and those living above 300% of the FPL around the time of the child's birth. (Income levels in these groups vary by family size and year, but in 2013, a family of four living under 200% of the FPL would earn about $47,100 or less, a family of four living between 200% and 300% of the FPL would earn between $47,100 and $70,650, and a family of four living above 300% of the FPL would earn more than $70,650.)

The authors also compared the effects of parents' separation and remarriage or re-partnering on children's behavior problems when children were 5 years old or younger versus when they were 6 to 12 years old.

While changes in family structure affected the behavior of children from high-income families, they didn't affect the behavior of children in low-income families. This may be because families with few economic resources at the outset may not experience as dramatic a change in economic circumstance when parents separate as those with greater initial resources, the researchers suggest.

Moreover, single-parent and blended families occur more often among lower-income families; in this context, single-parent and re-partnered families may be perceived differently.

For children from high-income families, the researchers found that the effects of family change varied by age. Parents' separation increased the likelihood that children would have behavior problems only if the separation took place when the children were 5 or younger. However, moving into a stepparent family benefited children's behavior only when it occurred after age 6.

"These findings suggest that both economic context and children's age are important to consider in understanding the effects of family structure on children," notes Ryan. "While economic resources in many ways buffer children, higher initial family income doesn't appear to be a protective factor when parents separate, at least for younger children."