Birth Order's Bottom Line

Oldest, youngest, middle, only...theories abound about how a person's place within the family birth order affects intelligence, ambition, personality and future relationships. 

How Many Siblings Does It Take to Save a Marriage?

Siblings may shield couples from divorce. But how many do you need?

So many factors can contribute to divorce. Can having a few or no siblings be a root cause for the dissolution of marriages? A new study, “Are There Long-Term Consequences to Growing Up Without Siblings? Likelihood of Divorce Among Only Children,” suggests this might be true. I need more proof.

Can growing up with siblings really hold your marriage together?

In the study, which used data collected from over 57,000 adults from 1972 to 2012, the researchers find that “each successive sibling lowers the probability of divorce by two percent.” They suspect that families with several siblings living together are ideal training grounds for learning how to get along with a spouse later in life. Coexisting with many family members may improve skills in diffusing conflicts, negotiating, and sharing.

However, it appears from the study’s results that families would need to have five or six or more children for their thesis to hold up—only finding, “significant differences emerging between only children and those with five or six or more siblings.” With the numbers of larger families having decreased during the years of their sample—in 1976, 20% of women ages 40 to 44 had five or more children, as compared to only 4% in 2006—it’s hard to say if family size is really a major dynamic in the divorce rate, which hovers at about 50%.

Several independent studies have pinpointed other elements that can strain a marriage, including a shy disposition, or even genes that dictate how emotions play a role in any relationship. It seems that chances of divorce are based on too many factors to know precisely what difference one sibling or seven siblings truly makes.

Are only children destined to divorce?

The “Long-Term Consequences to Growing Up Without Siblings” study also investigates why only children might divorce more often than children who were raised with siblings. The researchers presume that only children are often at a disadvantage: “If siblings serve as important social practice partners during childhood, individuals raised with few or no siblings may struggle to develop successful social lives later in adulthood.” This implies that only children are less likely to get along with others in adulthood and suggests the too often assumed “only child qualities” like an inability to cooperate or a selfish nature are what ultimately cause divorce.

Interestingly, Douglas Downey and Donna Bobbitt-Zeher—coauthors of the siblings and divorce study—found in a previous study that among adolescents, Growing Up Without Sibs Doesn't Hurt Social Skills. They asked 13,500 children in grades seven through 12 to name 10 friends. The only children were just as popular as their peers with siblings. Furthermore, the authors noted, "These results contribute to the view that there is little risk to growing up without siblings-or alternatively, that siblings really may be ‘good for nothing.’"

What I’ve seen is that parents who are positive role models in their marriage would likely be more significant in holding together a child’s future marriage than how many siblings are in the family.

What do you think? Does the number of siblings one has strongly affect a marriage?

Related: What Difference Do Siblings Make?, Fueling Stereotypes — A Cautionary Tale


Baker et al. “Shyness and Marriage: Does Shyness Shape Even Established Relationships?” Personality and Social Psychology Bulletin, 2010; 36 (5): 665

Bobbitt-Zeher, Donna, Douglas B. Downey, and Joseph Merry. Are There Long-Term Consequences to Growing Up Without Siblings? Likelihood of Divorce Among Only Children.

Haase, Claudia M. et al. “The 5-HTTLPR Polymorphism in the Serotonin Transporter Gene Moderates the Association Between Emotional Behavior and Changes in Marital Satisfaction Over Time.” Emotion, 2013; DOI: 10.1037/a0033761

Yen, Hope. “Census: Divorces Decline In United States.” The Huffington Post. 18 May 2011.

Zernike, Kate. “And Baby Makes How Many?” The New York Times. 06 Feb. 2009. 


Copyright 2013 by Susan Newman

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