I‘ve been happily married for more than 20 years and assume the same is true for my wife. While I like to think this is because I have won the marital lottery Powerball, it could be thanks to my sister.
Specifically, it could be a “positive” side effect of growing up with a sibling. I use quotes for those readers who may think divorce is actually the desirable outcome from their perspective.
I was recently asked to comment on a piece of US-based research looking at “the inverse association between the number of siblings and divorce” by Ohio State University sociologist Doug Downey and his team. In their most recent study, Downey and friends report on a comparative analysis of two large data sets from China and Europe. The China General Social Survey provided them with more than 11,000 Chinese participants who were surveyed many times between 2006 and 2017.
The average number of siblings for Chinese participants was 3.11. This sounds a lot to me, but as Downey notes, China’s one-child policy was started in 1979, and nine out of 10 of the survey participants were born before this.
Number of siblings is a fairly powerful “linear” predictor of marital maintenance in this Chinese sample. Every additional sibling predicted an 11% decrease in likelihood of divorce over the period of the surveys. Or, put another way, if you have four brothers or sisters, you’ve almost halved the chance of divorce.
For comparison, the Survey of Health, Ageing and Retirement in Europe provided more than 80,000 Europeans surveyed between 2004 and 2017. In this large group, the average “number of siblings alive” was 2.23. (For those interested, average siblings was 3.16 – about the same as for the Chinese sample.)
Again, siblings protect you against divorce – but to a lesser extent. Each additional sibling reduces your divorce “risk” only by 2.2%, meaning that Europeans need 20 brothers and sisters to get the same decrease as a Chinese person having four siblings. I feel for the mothers.
I‘m sure the more interesting question is why having siblings pays off in adult life and, specifically, marital longevity. Anyone who’s had a sibling will already have intuited part of the answer – growing up with siblings inevitably means growing up with conflict, but also more experience of conflict and (at least some of the time) resolution. It means having to experience balancing different wants and needs from your own. Not to mention having to share the spotlight, so it’s not all about you.
I think it’s also the case that the more someones you grow up around, the more difference you’re exposed to in how people work. Not to mention you get to observe role models (your parents) deal with those different ages and issues. A final point to note is that a big advantage of a larger family is when you need something, there are more people who can help out. When times are tough, you’ve got more folk you can turn to who, theoretically at least, have some incentive or obligation to help.
This isn’t to say that growing up a singleton means you’re a selfish attention-hogger who’s destined for multiple divorces. Notice that siblings aren’t 100% protective against divorce. Marriages are a tango of two, and there will be relationships in which the self-reliance or ability to occupy yourself without needing to rely on someone else is a good thing.
Why is the number of siblings more important for avoiding divorce in China than Europe? I’m not sure, and neither are Downey and colleagues, who predicted the reverse, on the basis that China is a more collectivist society and thus dilutes the socialisation that comes from siblings.
In terms of practical implications, short of building a time machine and going back to tell my parents to have more kids, I’m not sure there’s much more I can do here.
