Growing up with more than two siblings lowers your divorce risk

People who grow up with lots of siblings are more likely to marry -- and to stay married -- than are only children or those who grew up with one or two siblings, a new study has found.

Those of us who grew up in big families may get more practice suppressing the urge to strangle a bullying older brother in his sleep, or to stick an annoying little sister’s head in the toilet -- a useful exercise for sustaining a marital relationship. We may be more skilled in creating alliances with siblings when adversity outside or elsewhere in the family mounts. And the experience of never having the house to oneself may foster a distaste for being alone.

Whatever the explanation, when it comes to preventing divorce in adulthood, “the more siblings the better,” concluded a group of sociologists from Ohio State University, who presented their research Tuesday at the American Sociological Assn.

In a sample of 57,000 American adults surveyed at 28 points between 1972 and 2012, the researchers found that just 4% had grown up without any siblings. Of the 80% who had married at some point during the period studied, 36% had been through a divorce.

Among those who had married, each additional sibling a person had was associated with a 2% decline in his or her odds of having divorced. Only-children were not only less likely to marry than those with siblings; they were more likely to have divorced.

The study’s findings provide “one of the few pieces of evidence that siblings provide value,” acknowledged the researchers, Donna Bobbitt-Zeher, Douglas B. Downey and Joseph Merry. Research on the impact of siblings has largely found that only-children and those in smaller families fare better economically and in school. But with plummeting family sizes and an explosion of single-child families in industrialized democracies, researchers have begun focusing on the less tangible benefits of sharing a household with brothers and sisters.

Studies in the past decade have found substantial psychological differences between only-children and those with any siblings. But the Ohio State team found a subtler, more unexpected pattern in which “more is better.” In a subsequent analysis of their findings, the group noted that at around seven siblings, the divorce-prevention benefits of having additional siblings leveled off.

While the trend toward smaller families is well established in the United States, it is even stronger in several European countries, where families with a single child have become quite common. If supported by further research, the finding that such children may be less likely to marry and, if they do, more likely to divorce could result in significant demographic shifts, here and elsewhere, say the researchers.