Siblings are both similar and different. When you look at your friends, you may notice
family resemblances. Friends may look
like their siblings, or sound like them, or even have similar interests. At the same time, they are unique
individuals.
One particularly interesting aspect of the differences among
siblings is that their position in the family may affect who they are. There has been a lot of interest in the ways
that birth order may affect personality, achievement, and behavior. Research suggests that there are some
systematic influences of whether you are a first-born or later-born sibling on
aspects of your behavior.
In a 2001 paper in American
Psychologist, Robert Zajonc reviewed a number of studies on effects of the
order of birth on performance on tests of intelligence and academic
ability. He focuses on data suggesting
that both birth order and the size of a family affect academic
performance. That is, first born
children tend to do better on intelligence tests and tests of academic
performance than later-born children.
But, the larger the family, the worse that everyone in the family does
overall.
There are lots of reasons why birth order might affect
academic performance. Zajonc argues that
when families have fewer kids, they can spend more time with each child, which
tends to help them academically. In
addition, older children help to teach younger ones, which tends to help them
as well. If you have ever tried to teach
someone, you know that you have to learn it well yourself in order to be
helpful. So, older siblings end up
learning material better just because they have to help their younger siblings.
Birth order also affects risky behavior. Frank Sulloway and Richard Zweigenhaft
discuss this issue in a paper in a November, 2010 paper in Personality and Social Psychology Review. They looked at birth order and sports. First, they reviewed a number of studies
looking at the kinds of sports that people end up engaging in. They found that older siblings are generally
less likely to participate in risky contact sports than younger siblings.
Then, the authors analyzed major league baseball
players. Over the years, there have been
many sets of siblings who have both made it to the majors as baseball players. Overall, there was a tendency for younger
siblings to be more successful overall than older siblings. Younger siblings tended to have longer
careers and to play more games overall.
The biggest differences between older and younger siblings,
though, were in risky behaviors. For
example, one of the riskiest behaviors in baseball is the stolen base. Players try to move ahead on the base paths
by running from one base to another while the pitch makes its way from the
pitcher to the catcher. Once they were
on base, younger siblings were far more likely to attempt to steal bases than
their older siblings. Interestingly,
younger siblings were also more likely to be hit by a pitch than their older
siblings.
It wasn’t that younger siblings were just better athletes,
though. Older siblings tended to be
better pitchers than younger siblings.
They struck out more batters and walked fewer. These differences were small and not
statistically reliable. They do
demonstrate that the other differences are not just a matter of athletic
ability.
Why do older and younger siblings differ? Psychologists have given many explanations
for these differences, and chances are there are a lot of factors that
contribute to the differences. One
prominent explanation has to do with differences in family dynamics for older
and younger siblings. Older siblings get
a lot of their parents’ attention. First
children have a few years alone with their parents. After the first child, each child after that
has to do something to get some attention from the rest of the family. The argument is that later children have to
be more extroverted and more likely to take risks to get attention. And these sibling rivalries may continue into
adulthood. The behaviors that people use
to get the attention of their families as kids may continue to affect the way
they act long after they leave home.