How Birth Order Shapes Personality

The only child has trouble sharing, the oldest is bossy, everyone babies the baby, and the middle child is -- well, stuck in the middle. Are these merely stereotypes, or is there some truth to birth order differences? Although this theory only explains a small chunk of why we are the way we are, those differences definitely exist, claims birth order expert Frank Sulloway, PhD, author of Born to Rebel (Pantheon).

Personality doesn't hinge on the biological fact that a child is born first or seventh. "It's the roles siblings adopt that lead to differences in behavior," Sulloway says. Strategies children use to get parents attention differ depending on their position in the family lineup. And parents tend to reinforce these roles, whether they realize it or not. Here's an explanation as to why your child may develop the traits he does, depending on where he falls in the family tree.