Birth order stereotypes and why they're often wrong

Story highlights

  • Only 23 percent of women and 15 percent of men are a true match to their birth order profile
  • Nothing affects personality development more than genetics

Birth order myths aren't just fascinating cocktail-party talk. (You are totally a middle child!) There are solid psychological reasons why many people fit the mold. Here's a breakdown of the major stereotypes—plus the five "disruptors" that throw everything off.

The firstborn

    Stereotype: Natural leader, ambitious, responsible.
    Why it's true: The eldest, for a while, has no competition for time (or books or baby banter) with Mom and Dad. "There's a benefit to all of that undiluted attention. A 2007 study in Norway showed that firstborns had two to three more IQ points than the next child," says Frank J. Sulloway, Ph.D., the author of Born to Rebel. Firstborns tend to be surrogate parents when other siblings arrive, hence their protective and responsible nature.
    When it's not: Parents can set high expectations for a first (or only) child. "When he feels like he has disappointed his parents or can't measure up, he may veer off in another direction," says Kevin Leman, Ph.D., a psychologist and the author of The Birth Order Book.

    The middle child

    Stereotype: Social butterfly, peacekeeper, fairness-obsessed.
    Why it's true: "Middle-borns don't have the rights of the oldest or the privileges of the youngest," says Catherine Salmon, Ph.D., a coauthor of The Secret Power of Middle Children. As a result, they become experts at negotiation and compromise. They also tend to lean on their friends, as their parents' attention is often focused on the oldest or youngest child.
    When it's not: If the oldest doe