The term 'social father' is used for a person who is married to or cohabiting with the child's mother, but is not the biological father.
The study led by Lawrence M. Berger, PhD, MSW, of the University of Wisconsin-Madison also found that married and cohabiting biological fathers displayed relatively similar quality parenting, but the parenting practices of married social fathers were of higher quality than those of cohabiting social fathers.
Married social fathers were more engaged with children, took on more shared responsibility in parenting, and were more trusted by mothers to take care of children.
The survey with mothers showed that they perceived married social fathers to be engaged in relatively high quality parenting practices with the five-year-old children.
Most notably, social fathers exhibited significantly higher levels of cooperation in parenting than biological fathers.
"On the whole, our findings suggest that marriage is a better predictor of parenting quality with regard to social fathers than biological fathers," the authors wrote.
"Our study is relevant to understanding the quality of parental care that children receive from resident fathers across a range of family configurations that are now commonly experienced by children," he added.
The new study is published in the Journal of Marriage and Family.