Children raised by single mothers are more likely to fare worse on a number of dimensions, including their school achievement, their social and emotional development, their health and their success in the labor market. They are at greater risk of parental abuse and neglect (especially from live-in boyfriends who are not their biological fathers), more likely to become teen parents and less likely to graduate from high school or college.[i] Not all children raised in single parent families suffer these adverse outcomes; it is simply that the risks are greater for them.
Why are the children of divorced or unwed parents at greater risk of experiencing poor outcomes? There are a number of possibilities.
One possibility is that children in two parent families do better because of the increased resources available to them. Single parents only have one income coming into the house. On top of that, single parents often have to spend a greater proportion of their income on child care because they do not have a co-parent to stay home with the child while they work. Even beyond having more income, two parents also have more time to spend with the child. A recent study by Richard Reeves and Kimberly Howard finds that parenting skills vary across demographic groups and that forty-four percent of single mothers fall into the weakest category and only 3 percent in the strongest category.
The weak parenting skills found among single parents in the study may be related not only to the lack of a second parent, but to a lack of income and education as well. Education, in particular, stands out as the most critical factor in explaining poor parenting. But it is not clear that we should look at these variables in isolation from one another. In real life, compared to married parents, single parents tend to be poorer (because there is not a second earner in the family) and less well-educated (in part because early childbearing interrupts or discourages education), and this is what matters for their children.
Another possibility is that children born to unmarried mothers face more instability in family structure and that this instability results in worse outcomes for the child. In recent years, the focus of social science research has been less on the absence of a father and more on how family instability affects children. In fact, stable single-parent families in which a child does not experience the constant comings and goings of new boyfriends (or girlfriends) or the addition of new half siblings have begun to look like a better environment than "musical" parenthood.[ii]
Lastly, any discussion of the impacts of single parenthood must take into account selection effects. Single parents may be more likely to have other traits (unrelated to their marital status) that cause their children to have worse outcomes than children raised in two-parent homes. It may not be the divorce or unwed birth that causes the problem but instead the underlying personal attributes, mental health or competencies that produce both a broken family and worse outcomes for the child.
Children who end up in a single parent family as the result of the death of one parent do not have the same poor outcomes as children raised by single parents due to a divorce or out of wedlock birth. This may be because death, unlike divorce or out-of-wedlock childbearing, is more likely to be a random event, not connected to the attributes or temperaments of the parents. The lesser disadvantages for children ending up in a single parent family as the result of the death of one parent may reflect this fact and point to the importance of taking unobserved attributes, temperaments or behaviors into account when talking about the consequences of single parenthood for children.
[i] McLanahan and Sandefur, Growing up with a Single Parent; Jane Waldfogel, Terry-Ann Craigie, and Jeanne Brooks-Gunn. "Fragile families and child wellbeing."The Future of children (2010), p. 87.
[ii] Waldfogel, Craigie, and Brooks-Gunn, "Fragile families and child wellbeing."