What do we know about the genetic side of autism?

And if there is something, why can’t we diagnose it in utero?

You can’t diagnose it in utero because there is no “autism gene”, although studies have pointed out that the genetic heritability of autism spectrum disorder is high. In the UK, some studies done by the Medical Research Council found that genetic influences on autism are estimated to be between 74-98 percent. That’s a lot!

The consensus is that genes are the primary driver of autism, however we don’t know which genes.

There is one genetic mutation that both children on the autism spectrum and highly gifted children (prodigies) have in common. This is the paper where you can find more: https://www.karger.com/Article/Abstract/373890

It’s super frustrating that we still don’t know much, but there’s ongoing research. I think there are around 200 or so genes related to autism, but not a lot of accuracy.