 However, inbreeding also gives opportunity for genetic purging of deleterious alleles that otherwise would continue to exist in population, and can potentially increase in frequency over time.Another possible negative effect of inbreeding is weakened immune system due to less diverse immunity alleles.A review of the genetics of inbreeding depression in wild animal and plant populations, as well as in humans, led to the conclusion that inbreeding depression and its opposite, heterosis (hybrid vigor), are predominantly caused by the presence of recessive deleterious alleles in populations.