Health, in order

New research shows that birth order may just have an effect on your health. Here are a few findings, as compiled by, and why they might be true:

Firstborns …

… score an average of three points higher on IQ tests than younger siblings.

… are more likely to suffer from allergies, hay fever, eczema and asthma. Scientists say this may be due to firstborns being overprotected and kept out of germs’ way.

… have higher rates of testicular cancer, possibly because they are exposed to higher levels of estrogen in the womb.

Middle children …

… have 5 percent lower risk of gum disease, probably because their immune systems were exposed early to their older sibling’s germs.

… have higher risk of depression, possibly due to more attention being paid to older and younger siblings.

Youngest children …

… have a lower risk of developing allergies or Hodgkin’s disease.

… in big families are 50 percent more likely to be injured, due to lax supervision.

… go through puberty an average of three months earlier than their older siblings, meaning they’re more likely to start having sex earlier. They’re also more likely to smoke cigarettes and engage in other risky behavior.