Incestuos mother-som matings which result in pregnancy do occur. Males can develop intense sexual friendships with one another, especially between older and younger males. Capuchin monkeys Cebus albifrons . Young males often suck and fondle the scrotum of older males. Common Chimpanzee Pan troglodytes.
Mothers engage in sexual activity with their infants fairly often.
Gorrilla Gorilla gorilla . Younger animals frequently participate in non-penetrative sexual activity. Langurs and Leaf Monkeys Nilgiri langur and Presbytis tellus. A large proportion of male Hanuman Langurs are non-breeding. Sexual interaction between adults and juveniles has not been observed.