Question: [The lectures] briefly mentioned sexuality as something that you're born with - is it due to a gene, and if so, could people alter their unborn children's sexuality or could this gene cause either fluid or rigid sexuality?
I do not do research in this area, but from what I know of the literature there is evidence for a genetic contribution to non-heterosexual behaviour (i.e., genes explain about 1/3 of the differences we see between people in terms of their sexual orientation). Genes are not the whole story , but seem important.
These articles would be a good place to start if you wanted to learn a bit more. The most important message is that while genes play a role – there are lots (and lots) of them. There is not ‘one gene’ for sexuality, so trying to edit or change gene function by genome editing would probably be a futile (and very expensive task)!