Incest

Incest occurs when two related individuals nest and have offspring. Directly related creatures (siblings and parents/children) will receive the negative affects from incest. Other family members, such as grandparents, grandchildren, uncles/aunts, nieces/nephews, and cousins will not receive the affects of incest if they choose to nest together.

As 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.