Question: do male cats not find it wierd mating with their mother or sister

Kevin Mahon answered on 14 Jun 2012:

Cats, like most animals tend to avoid mating with close kin, not because they find it ‘weird’ but as they can tell close relatives and kin resulting from the mating of close relatives are usually less fit as they are inbred.

As an animals ultimate purpose is to pass on its genes and for it’s offspring to do so as well, close inbreeding such as this is not typical and only occurs in extreme circumstances.