Handedness

Handedness is a better (faster or more precise) performance or individual preference for use of a hand, known as the dominant hand. Handedness is not a discrete variable (right or left), but a continuous one that can be expressed at levels between strong left and strong right. There are four types of handedness: left-handedness, right-handedness, mixed-handedness, and ambidexterity. Left-handedness is somewhat more common among men than among women.Wikipedia

Both environmental and genetic factors influence handedness. Genes reported to influence handedness include LRRTM1, PCSK6, and AR. However, the variance in handedness explained by any one factor factors is low, and initial findings are often not replicated (or replicable). McManus et al. ([PMID 23631511]) estimated the number of genetic loci involved in handedness to be at least 30–40, and possibly much larger.[PMID 25426097]