Theories on Handedness

Because it develops so early, this brain asymmetry appears to be largely innate. It is possible, however, that environmental factors begin operating even before birth. One hypothesis is that the right hand becomes more skillfull because it has greater freedom to move in the womb. About three-quarters of all fetuses spend the last several weeks of gestation with their right arm facing out—toward the mother's abdominal wall. This arm has more space in which to move than does the left arm, which...

 Practicing Motor Skills

In fact, babies do improve their motor skills much as adults do—as a result of diligent practice. New skills, such as walking independently, don't suddenly emerge out of nowhere but gradually build out of prior, simpler abilities—kicking, standing, and walking with support—after weeks or months of trying. The only difference between infant and adult motor learning (aside from the fact that infants seem to crave the exercise more than most of us) is that babies can train themselves in a partic...