For example can 2 dog siblings have sex and reproduce? Does it happen?
Most Helpful Guy
Yes. It happens, but it's less of a problem for animals since they don't practice monogamy.
It happens in humans too. Just read the Bible.2
Most Helpful Girl
It definitely happens. Animals don't know any different. I have friends who have a farm and they have to bring in new cats every so often for "fresh blood" bc they get so inbred they are messed up after a while. Really sad but it's nature.1