On the relationship between handedness and season of birth for men.

A sample of 8,929 male baseball players and a sample of 2,234 males from the U.S. National Health and Nutrition Examination Survey are used to assess the relation between handedness and season of birth. The results, when coupled with a further examination of the 1991 data of Dellatolas, Curt, and Lellouch, lead to the conclusion that those born during the spring and early summer are more likely to be left-handed than are those born during the fall and winter.