If someone discovered a reliable way to detect the future sexuality of a child then those efforts would suddenly be contradicted, because 1) it would be harder to argue that it's not just a condition, and 2) no matter how controversial, there would be a demand for such screenings, and the LGBTQ-community would most likely interpret it as an existential threat.
Obviously, I chose sexuality as an example as it's an easy metaphor that most people get, but this reasoning can be applied to quite a few other things that are (possibly) caused by genetical factors and where there's a community involved. As an example, I've heard people mention an on-going "genocide" of people with Downs syndrome, simply because pre-natal screenings are quite effective at detecting it and that parents therefore terminate the pregnancy instead of having a child with Downs.
EDIT: Simply put: If you start screening for X, thereby allowing it to be prevented or treated in any way, then you imply that the X is something negative. People with X might take offence to that.
We can. Humans are equal in dignity and rights. That doesn't say anything about genetics.
The Egalitarian Fallacy
https://link.springer.com/article/10.1007/s11406-019-00129-w
When we compare to Pre-K programs and other current enhancement that can be bought with money, they are no guarantee that the enhancement will go to the next generations, unless the family can keep paying for those things in the future. So the issue is the starting point of the human life.
Today, we still can believe that all human are born "equal"; but the moment a whole set of human beings are enhanced on a genetic level, a lot of our moral values will be changed forever.
No longer we can say that "All human beings are born free and equal in dignity and rights." if that happens, it will upend things like the "Universal Declaration of Human Rights" and many other concepts that today's society relies on to organize itself. Imagine to live in a society where you are genetically "inferior" and there is no way you can "change" or upgrade who you are.