In animals, DNA was a genetic substance in the body containing units called genes, which contained the genetic information of an individual. Except for unaltered clones and identical twins, DNA was unique to each individual. Depending on what genetic material was inherited from the parents, the presence or absence of some genetic material could influence the appearance of an individual, with certain segments influencing hair (or fur) color, eye color, height, body type, the ability to use the Force, and the aging process, among other things.