Inbreeding is the mating of closely related individuals, such as siblings or parents and offspring.

Inbreeding can increase the risk of genetic disorders because it increases the likelihood that offspring will inherit two copies of the same harmful gene.

Down syndrome is not caused by inbreeding. It is caused by an extra copy of chromosome 21.

All of the above endangered species have been affected by inbreeding. Giant pandas have been inbred for centuries, which has led to a decrease in genetic diversity and an increased risk of genetic disorders. Cheetahs are also inbred, which has led to a high incidence of a deadly genetic disease called cheetah immunodeficiency virus (FIV). Black rhinoceroses have been inbred due to habitat loss and fragmentation, which has led to a decrease in genetic diversity and an increased risk of extinction.

All of the above methods can be used to reduce the effects of inbreeding in endangered species. Increasing the population size will reduce the likelihood that individuals will mate with close relatives. Introducing new individuals from other populations will increase genetic diversity. Using artificial insemination to breed individuals from different populations will also increase genetic diversity.