A federal study released in 2011 showed that children living with their biological mother and her boyfriend were 11 times more likely to be sexually, physically or emotionally abused and six times more likely to be neglected than children who lived 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," Wilcox wrote at the time the study was released.
The study also showed that even if children were living with their biological parents, they were four times more likely to be abused and three times more likely to be neglected if those parents were cohabiting rather than married.
This information was reported in the Fourth National Incidence Study of Child Abuse and Neglect (NIS-4) Report to Congress, and examined cases of child abuse between the years of 2004-2009. The data corroborated information from previous studies, several of which have shown that children living with unmarried adults were more likely to experience abuse and neglect, including a 2002 study which found that more than 15 percent of children living in cohabitating homes experienced serious emotional problems such as depression, compared to just 3.5 percent who lived with their biological married parents. Another 2005 study found that children living with their mother's boyfriends were 45 times more likely to be killed than children living with their biological married parents.
The data shows that marriage is often a safe and stabilizing force in children's lives, and it may help insulate them from other problems, Wilcox said.
"We know that kids are more likely to thrive in a stable routine with stable caregivers, and we know too that kids who are experiencing a lot of family instability are more likely to fall prey to adults who are targeting them for abuse," he said.