It's at least mostly BS. Researchers have found certain genes which have a weak statistical correlation with high IQ but the mechanism of action is unknown. And it's not an additive thing: the interactions and relationships between individual genes must play some role but that has barely been studied at all. There's no guarantee that an embryo with those genes will grow up to be intelligent, or that they won't have other problems. But there's enough "dumb money" in Silicon Valley to provide a customer base of insecure suckers for these startups.

https://www.wsj.com/us-news/silicon-valley-high-iq-children-...

Fertility is a field with a lot of weird BS because it’s mostly direct pay and there’s no insurance company to deny bullshit.

They probably do some weird test, then pick the embryos that look the prettiest. How do you prove that little Jimmy wasn’t the smartest embryo?