Research compiled from the General Social Survey found that the number of siblings you grow up with impacts your marriage in adulthood. According to the study presented on August 13, 2013 at the 108th meeting of the American Sociological Association in New York by researchers Donna Bobbit-Zeher and Doug Downey of Ohio State University, the more siblings you have, the less likely for your marriage to end in divorce.
Apparently having no siblings, or just one or two, makes little difference in terms of divorce, but in comparison to larger families, "there is a meaningful gap in the probability of divorce." The researchers calculated that divorce becomes increasingly unlikely for adults with several siblings, by about 2% for each additional brother or sister. Donna Bobbit-Zeher thinks that "having more siblings means more experience with others - and that seems to provide additional help in dealing with a marriage relationship as an adult."
As this is the only study on the topic, demographer Paul Amato of Pennsylvania State University says that "it would have to be replicated multiple times before you can have too much faith in it." A different study published in 2011 in the Journal of Family Issues found that "adults who grew up without siblings do not appear to different from others in their patterns or frequency of interaction across a wide variety of social interactions," but a closer look at divorced couples shows that having children is a significant factor in the likelihood of divorce. The statistics According to My Divorce Papers report in July, couples with no children have a 48% likelihood of filing for divorce. One child lowered the odds to under 22% and having four or more children decreased the chance of divorce to under 1%. Kids, whether siblings or offspring, seem to decrease the likelihood of marriages ending according to both of these university studies.
The General Social Survey is sociological data from interviews with 57,000 adults across the United States between 1972 and 2012, collected by the National Opinion Research Center at the University of Chicago.