When B. J. Upton hit a home run last year to help the Tampa Bay Rays defeat the New York Yankees, it was not the first time that day that Upton had gone deep. Just a few hours earlier, chatting in front of his locker, he had helped confirm the results of a recent study of sibling risk-taking behavior.

In the Personality and Social Psychology Review, Frank J. Sulloway and Richard L. Zweigenhaft went digging for evidence of siblings behaving differently in the vast database of baseball statistics. Given how younger siblings have been shown to take more risks than their older counterparts — perhaps originally to fight for food, now for parental attention — Drs. Sulloway and Zweigenhaft examined whether the phenomenon might persist to the point that baseball-playing brothers would try to steal bases at significantly different rates.

In fact they did: For more than 90 percent of sibling pairs who had played in the major leagues throughout baseball’s long recorded history, including Joe and Dom DiMaggio and Cal and Billy Ripken, the younger brother (regardless of overall talent) tried to steal more often than his older brother.  Proof your kid brother has always tried to one up you.

Birth order matters.  And not just in fielding a baseball team.  As an All Pro Dad, find out the 10 ways birth order affects your children.

Huddle up with your wife tonight and ask:  How much do you believe birth order plays a role in shaping our children’s attitudes?  Why?