Contrary to Hollywood stereotypes, attractiveness and IQ are extremely strongly correlated. You can find a million studies affirming this with a search - it's not controversial, though the reason for it is. For the lazy here's a random study. [1] The typical effort to dismiss it is to claim it's a bias or halo effect.

But as that paper lays out there's a really simple and logical explanation for it as well. Intelligence is highly heritable, attractiveness is highly heritable. Intelligent people are more likely to succeed making them more able to seek out other attractive/intelligent individuals, thus resulting in more attractive/intelligent offspring.

[1] - https://www.sciencedirect.com/science/article/abs/pii/S01602...