Sexual orientation, just like intelligence and quite probably a lot of other traits, likely involve more than one gene. Maybe lots more. Seems to me what thus company is offering is the possible opportunity to lessen the risk of having a child with an unwanted trait or traits. If they suggest anything else, they’re peddling snake oil.
Please note, I am NOT suggesting that, if they can do what they say, this is ethical.
To me, suggestions that homosexuality is genetic are just as crazy as suggesting that subscribing to the New York Times is genetic.
These are learned behaviors. Nature pulls HARD in the other direction, so we are talking severe trauma involved.