How sisters and brothers shape our lives

By Rita R. Robison

Being the youngest of three girls, sibling relations always intrigue me.

When I saw Jeffrey Kluger ’s book, “The Siblings Effect: What the Bonds Among Brothers and Sisters Reveal About Us,” I wanted to learn more.

Kluger, a senior writer and editor at Time Magazine, wrote the book because he believes sibling relationships are, in many ways, the most important relationship in our lives. They’re also, he said, the last unexplored frontier of family relationships.

It was only in about 2005 that the field of sibling research began to develop. The more he read about it, the more Kluger thought that it was a field worth exploring.

This led to two cover stories he wrote for Time – one in 2006 on sibling science and one in 2007 on birth order.

Among the findings in Kluger’s book:

• Firstborns are smarter. If you’re a firstborn, chances are you’re the smartest sibling in the family, with a 3-point IQ advantage over the second born. The second born, in turn, has a 1.5-point advantage over the third. But don’t worry if you’re the last of 12: The IQ decline flattens out after three or four children.

• Men with sisters are better listeners. Men who grew up with sisters are generally rated by female dates to be better listeners than men raised only with brothers. Women who grew up with brothers, similarly, are considered by male dates to be tougher and more easygoing than women who grew up with only sisters.

• Younger siblings are more empathetic. If you’re the youngest or physically smallest in your family, you may be better than your siblings at intuiting other people’s thoughts and feelings. This kind of interpersonal antenna is what psychologists call a “low-power strategy” – a way of countering the high-power strategy of a bigger or older sibling.

• The benefits of siblings helping to raise siblings – and why some cultures benefit more than others. Older children help to co-parent their younger siblings in all cultures. But, that tradition has remained much stronger in some cultures than in others, and both older and younger siblings benefit as a result. Among native Hawaiians, for example, co-parenting siblings not only improve their academic performance and their parenting skills, but also learn primal lessons about empathy, generosity, and selflessness. Chinese Americans benefit in similar ways and have also been shown to develop less depression in their teen years than kids who have been given little or no responsibility for their younger siblings.

• Smoking, alcohol, drugs – and especially pregnancy – are contagious.  The presence of an older smoking sibling makes a younger one four times likelier to start. The same is true of drugs and alcohol. For teenage pregnancy, the problem is even worse: A younger sister is five times likelier to be a teen mom if her older sister is one already.

• Why athletes and actors follow scholars. Good students don’t necessarily skip generations, but they may skip birth-order spots in nuclear families. If a first-born is a straight-A student, a second-born may excel at something else – sports or theater, for example. This so-called de-identification is a way of being recognized for something unique to you.

• Singletons aren’t deprived. Singletons who tend to double-down on their relationships with their friends and cousins usually make up for the lack of in-house peers. Singletons also tend to develop better vocabularies and more sophisticated senses of humor since conversation and TV choices in the home are likelier to reflect the parents’ preferences. In addition, studies show that they do as well, if not better than, children with siblings by virtually any measure.

• Birth order can be dangerous to your health. Surveys show that younger siblings are less likely to be vaccinated than older ones. Kids with at least two older siblings are 50 percent likelier than other children to be taken to an emergency room with asthma-related breathing problems, probably due to infectious agents brought into the home by the older children. Second and third children also have a higher risk of diabetes than their firstborn siblings, with a 43 percent increase in cases for every five years of maternal age at birth.

• Keep up your sibling relationships – they’re the only ones that last a lifetime. As life spans get longer and more people are making it into old age – often having lost a spouse – sibling relationships are more important than ever. If your relationships with your siblings are good, keep them that way. If they’re not, work to repair them.

Copyright 2011, Rita R. Robison, Consumer Specialist