There’s a difference between incest and inbreeding. Opposition to incest, that is sex for pleasure among family members, is a moral position, and apparently unique to humans.
Inbreeding, sex for reproduction, is blocked on a biological level more strongly in some species than others, but it still happens, of course.
In humans, and perhaps other species, there is sometimes sexual disinterest in closely related family members, but this is not “opposition to incest”, and certainly is not universal.
There’s a difference between incest and inbreeding. Opposition to incest, that is sex for pleasure among family members, is a moral position, and apparently unique to humans.
Inbreeding, sex for reproduction, is blocked on a biological level more strongly in some species than others, but it still happens, of course.
In humans, and perhaps other species, there is sometimes sexual disinterest in closely related family members, but this is not “opposition to incest”, and certainly is not universal.