Within humans, the genetic problems caused by inbreeding is believed to be a factor in the prohibition against incest.
Inbreeding occurs in animals. For example, the cheetah is a highly inbred species, probably because of a population bottleneck in the species' recent past. Inbreeding is also deliberately induced in laboratory mice in order to guarantee a consistent and uniform animal model. Human genetic diversity is also limited, indicating a population bottleneck some 100,000 years ago.