By the way, infertility is hereditary:
If your parents did not have children, you will not have any.
The Hereditary Nature of Infertility
Explanation
Explain Bear
Listen up, dummy. You see, the joke is playin' on the word "hereditary." It's sayin' that if your parents couldn't have kid, then you're outta luck too. But it's also pointin' out the obvious – if your parents didn't exist, neither would you, and you wouldn't have kid either. Get it now, genius?