There are over 200 hereditary traits that are transmitted from generation to generation in humans. Traits are determined by alleles, which can be dominant or recessive. When an individual has two different alleles, one allele will be expressed as the dominant trait while the other allele requires two copies to be expressed as the recessive trait. Some common examples of dominant and recessive traits in humans include widow's peak, bent pinkie, earlobe attachment, rolling of the tongue, cleft chin, dimples and handedness being dominant, while straight hairline, straight pinkie, attached earlobes, inability to roll the tongue, smooth chin, lack of dimples, and left-handedness being recessive