Some people seem worried about this attitude. But unless our society degenerates into a totalitarian state I don't think we have anything to worry about.
It would be just like some people purposefully avoid interracial relationships. Some parents would choose to make sure their kids were straight.
And some militant gay parents would do the opposite, particularly as a backlash against reports of straight parents making sure their kids are straight.
But most people would opt not to touch that one.
Some may decide "bisexuality" on the grounds of their kid never having to grow up and find that the best person for them is the wrong sex.
Some may decide "Asexuality" if they want their kid to focus more on careers and studies.
But I bet other facets of sexuality will be more popular as targets for manipulation. If we could make it so people would be more attracted to intelligence and less concerned with appearance for example that would be a big plus.
The government's role should be to guarantee product safety. So if clinical trials show that a modification is safe it should be allowed. If it's to cure a serious illness then gene therapy could be mandatory (when having a child) for some things.
To make neurodiversity advocates happy some mild ADHD or Aspergers Syndrome could be allowed to remain, parents' choice. Some 'illnesses' are more like tradeoffs some negative traits come along with some positive traits (don't want to 'cure' the next Einstein or Bill Gates). Drawing the line in these cases will be tricky, but considering the worst cases a line does need to be drawn. If it can be fixed there's no reason to have people who spend their whole lives unable to speak or take care of themselves.
In time gene therapy (and other therapies as it's more complex than that) would extend to adults so adults who don't like what their parents chose for them could reverse it.
It's a long, long ways off but if it were here and were possible I would choose to have wings.