W. Bradford Wilcox, Director of the National Marriage Project at the University of Virginia and a senior fellow of the Witherspoon Institute writes in the Public Discourse that "Cohabitation does not serve the “best interest” of children, regardless of what the courts say."

[According to a new federal study,] children living with their mother and her boyfriend are about 11 times more likely to be sexually, physically, or emotionally abused than children living with their married biological parents. Likewise, children living with their mother and her boyfriend are six times more likely to be physically, emotionally, or educationally neglected than children living with their married biological parents. In other words, one of the most dangerous places for a child in America to find himself in is a home that includes an unrelated male boyfriend—especially when that boyfriend is left to care for a child by himself.

But children living with their own father and mother do not fare much better if their parents are only cohabiting. The federal study of child abuse found that children living with their cohabiting parents are more than four times more likely to be sexually, physically, or emotionally abused than their peers living in a home headed by their married parents. And they are three times more likely to be physically, emotionally, or educationally neglected than children living with their married biological parents.

... This latest study confirms what a mounting body of social science has been telling us for some time now. The science tells us that children are not only more likely to thrive but are also more likely to simply survive when they are raised in an intact home headed by their married parents, rather than in a home headed by a cohabiting couple.