How about this? If you pass on your bad genes, you can't yell at your kids.
I feel this way when I see an unkempt, obese, fanny-pack-donning mom, and her dumpy, acne-faced clone of a daughter, and the mom yells at the daughter for something stupid. I wanna be like, "Don't yell at her! Haven't you done enough to this poor girl already?! Don't add insult to injury. If she's an idiot, it's your fault!"