Incest

Incest occurs when two related individuals nest and have offspring. Directly related creatures will have the highest chance of having incest, while subsequent generations will not experience as harsh of effects from mating. It takes about 3 generations for incest to disappear.

When children of incest become adults, they inherent negative talents from their parents, making it harder to survive.

A baby Parasaurolophus with incest. As you can see, it has received many negative talent nerfs from its parents.