Growing up with siblings may provide some protection against divorce as an adult, according to a new study.
Each additional sibling a person has (up to about seven) reduces the likelihood of divorce by 2 per cent.
The practical difference between having no siblings and having one or two isn't that much in terms of divorce, said Doug Downey, co-author of the study and professor of sociology at The Ohio State University.
"But when you compare children from large families to those with only one child, there is a meaningful gap in the probability of divorce," he said.
One of the biggest surprises of the study was that it wasn't the difference between being an only child and having siblings that was significant.
"We expected that if you had any siblings at all, that would give you the experience with personal relationships that would help you in marriage," said Donna Bobbitt-Zeher, co-author of the study and assistant professor of sociology at Ohio State's Marion campus.
"But we found that the real story appears to be how family dynamics change incrementally with the addition of each sibling. More siblings means more experience dealing with others, and that seems to provide additional help in dealing with a marriage relationship as an adult."
The study used data from the General Social Survey, which involved interviews with about 57,000 adults from across the United States at 28 points between 1972 and 2012.
The results showed that each additional sibling up to about seven provided additional protection from divorce, Downey said. More siblings than that didn't provide additional protection, although they did not hurt, either.
The researchers took into account a wide variety of other factors that may have affected the results, including education, socioeconomic status, family structure, race, age at marriage, whether the respondents had children, gender role attitudes and religious affiliation, among others.
"When we added in all of these controls, nothing took away the relationship we saw between siblings and later divorce," Bobbitt-Zeher said. "None of these other factors explained it away."
While the study itself can't explain the protective effect of having siblings, Downey said there are good reasons for the findings.
"Growing up in a family with siblings, you develop a set of skills for negotiating both negative and positive interactions. You have to consider other people's points of view, learn how to talk through problems. The more siblings you have, the more opportunities you have to practice those skills," he said.
"That can be a good foundation for adult relationships, including marriage."