Inbreeding is the production of offspring from the mating or breeding of individuals or organisms that are closely related genetically. By analogy, the term is used in human reproduction, but more commonly refers to the genetic disorders and other consequences that may arise from expression of deleterious recessive traits resulting from incestuous sexual relationships and consanguinity. Animals avoid incest only rarely.
Common fruit fly females prefer to mate with their own brothers over unrelated males.
Heterozygous
Banded mongoose females regularly mate with their fathers and brothers.
White tiger in Gunma Safari Park
Incest is human sexual activity between family members or close relatives. This typically includes sexual activity between people in consanguinity, and sometimes those related by lineage. It is forbidden and considered immoral in most societies, and can lead to an increased risk of genetic disorders in children in case of pregnancy.
Egyptian king Tutankhamun married his half-sister Ankhesenamun.
Maya king Shield Jaguar II with his aunt-wife, Lady Xoc AD 709
Charles II of Spain was born physically disabled, likely due to centuries of inbreeding in the House of Habsburg, and suffered a particularly pronounced case of Habsburg jaw
Maximilian II, Holy Roman Emperor married his first cousin Maria of Spain.
