Web Exclusive: The New Science of Siblings

Po Bronson is the co-author of "NurtureShock" with Ashley Merryman.
You can read an excerpt from the book by CLICKING HERE.

Growing up, my brothers and I fought all the time. We bickered, competed, and pummeled each other. But we also played together endlessly, from morning to dusk, indoors and out. We played every sport in the backyard, built forts in trees, jumped off ramps on our bikes, swam in the lake, and built elaborate haunted houses in our basement.

According to Dr. Laurie Kramer, one of the world's leading experts on sibling behavior, the fact we played together so often matters more than the fact we fought so often, which is why my brothers and I have such close friendships as adults today.

Po Bronsons "NurtureShock" uses science to offer insight into parenting.Play

For over twenty years, Kramer has tracked sibling pairs from infancy through adulthood. She's isolated the secret indicators in childhood which predict siblings' futures. It turns out that the ratio of playing together to fighting together is key; there have to be more good times than bad times. Siblings who don't fight -- but don't play together either -- end up not having warm relationships as adults.

Sibling quarrels are a fact of family life. On average, young siblings argue or fight 3.5 times an hour, which adds up to ten minutes of every hour. In observational studies, siblings make 700 percent more negative and controlling statements to each other than they do to friends.

Why? Because if you treat a friend badly, they'll eventually stop being your friend. Siblings, meanwhile, will be there tomorrow, no matter what. In the words of one scholar, "Siblings are genetically sentenced to live together, with no time off for good behavior." There's no incentive to treat each other better.

Kramer's body of research suggests that parents should worry less about how they break up sibling fights, and concentrate more on teaching brothers and sisters the skills of initiating play together. It's not about conflict resolution, it's conflict prevention: Less fighting will be the consequence of siblings initiating play in an amicable manner.

Conventional wisdom holds that children learn social skills at home, with their siblings, then apply that template to their friends. Kramer's work says it's the other way around. In her long-term studies, she was able to videotape older siblings playing with their best friend before their younger sibling was born. Their style of playing together became the older sibling's template to use on the younger sibling a couple years later.

In fact, one element of their play was especially foretelling: Older siblings who could enjoy shared fantasy play with their best friend in a mutual, reciprocal style went on to have great relationships with the younger siblings, years and decades later.

Kramer's work calls into question what both parents and kids are reading (and learning) about sibling relationships. In parents' case, the 47 most popular parenting manuals all suggest that sibling conflict is rooted in an eternal struggle to compete for parents' affection -- a theory first promoted by Freud.

But empirical polls of kids say otherwise: fighting for parents' attention ranks dead last in the list of what brothers and sisters say they fight over. If you think about it for a second, this makes sense -- even when all children in a family get plenty of attention, siblings will still quarrel.

And what do parents turn to, for help? Often, it's childrens' books that portray brothers and sisters learning to get along. Kramer analyzed the 261 most popular such books and videos. Despite their happy endings, the first half of these stories model all sorts of ingenious ways for siblings to taunt, belittle, and blame each other.

Young readers actually learn from the characters new undermining techniques they'd never considered. So when Kramer gave a control group of families these books to read daily, the siblings' behavior didn't improve -- it got worse so quickly Kramer had to stop the study.

When I was a child, my parents would agonize over the battles I had with my brothers. They warned us we'd end up hating each other. But the one thing they got right was they never separated us -- they never forced us to play apart, to avoid conflict restarting.

We'd sulk for an hour, sure, but usually, (maybe always), we'd be playing again before nightfall. We never got around to saying "sorry" or resolving who started it. It turned out that was okay-- it was starting the games again that mattered.