Quote from Phoebe in The One with the Fertility Test
Rachel: All I'm saying is, I don't think that Joey and Charlie have anything in common. Ross: I don't know. They seemed to have a shared interest in each other's tonsils. Phoebe: Wow. Joey and a professor. Can you imagine if they had kids? And if the kids got her intelligence and Joey's raw sexual magnetism, those nerds would get laid!