inbreeding, mating of closely related organisms. Inbreeding is chiefly used as a means of insuring the preservation of specific desired traits among the offspring of purebred animals (see breeding). Continued inbreeding through many generations reduces the chances for diversity of characteristics in the offspring and tends to reduce vigor and fertility. Only in laboratory conditions can the unwanted characteristics that frequently result from inbreeding be selected out of the strain and selection for purely advantageous traits be carried out. The necessarily uncontrolled cases of inbreeding among humans (as in closed societies or within royal families) have generally proved deleterious, and inbreeding is therefore discouraged in most societies (see consanguinity; incest).