Hybrids

For some strange reason, monsterpeople and humans seem to have some kind of strange biological connection that makes it so, despite their obvious differences, they can mate and often have children. These children show physical features from both of their parents. They are known as hybrids.

Hybrids usually obtain mostly human features (due the human genes being more dominant than the monster genes), but they always obtain something from their monster side.

There are a few exemptions:

Although dopplegangers are considered monsterpeople, they give birth to children who contain the EXACT features of their particular genders parent. Therefore doppleganger couples do not produce hybrids at all, but CLONES. There have been known cases of inbreeding in doppleganger families to create armies of clones that sadly, begin to deteriorate and become less like clones, due to birth defects. That means you can never have an army of clones unless you know some serious science shit.

There is also a very VERY rare occurance that is often considered magic due to how batshit the concept is, but occasionally monsterpeople who have animalistic traits will GIVE BIRTH TO ANIMALS.

That means catgirls will occasionally give birth to litters of kittens, and doggirls to litters of puppies and so forth.

Seriously. You do not understand the meaning of disturbing until you watch your sharkgirl wife give birth to a full baby tiger shark.