Handedness

Even identical twins with the same genes can differ in handedness: one may be left-handed and the other right-handed. Such discordance in twin studies shows that although genes influence handedness, they do not determine it alone.

About 10% of people worldwide are left-handed. A 2020 meta-analysis covering more than two million people estimated the best overall prevalence at 10.6%—confirming the familiar figure of roughly one person in ten.