> I wonder if / how long it will be before parents have the technical means—if not the legal right—to alter their child to be gay or straight through gene therapy.

I'm not sure that'll ever be possible. Once a gene has "done its work", possibly when the fetus was in the womb, that least to homosexuality (or whatever other characteristic is of interest), then editing the genome will have less or no effect.

> Or even simply selectively bring to term one orientation or the other.

This seems a lot more doable to me.

I expect it will be possible by 2025-2030.