It's never made much sense that the entire multi-species Federation would be subject to a strict ban on genetic engineering due to events on Earth that happened centuries before the Federation was even founded. The way they doubled down on that rationale in Una's trial only highlighted the absurdity -- especially when Admiral April claimed he would exclude Una to prevent genocide.
On the one hand, the writers may be trying to create a straw man out of a weird part of Star Trek lore so they can have a civil rights issue in Starfleet. And that's fine. From an in-universe perspective, though, I think we can discern another reason for the ban on genetic engineering -- the Klingon Augment Virus.
There was a ban on genetic engineering on United Earth, which is understandable given that it was much closer to the time of the Eugenics Wars. Why would that remain unchanged when more time passed, more species joined, and more humans lived in places without living reminders of the war? [NOTE: I have updated the paragraph up to this point to reflect @Value Subtracted's correction in comments.] The answer is presumably that they needed to reassure the Klingons that something like the Augment Virus would never happen again. Hence they instituted a blanket ban around that time -- perhaps in 2155, the year after the Klingon Augment Virus crisis and also, according to Michael Burnham, the year the Geneva Protocols on Biological Weapons were updated.
That bought the Federation over a century of peace, but after war broke out due to a paranoid faction of Klingons who thought humans would dilute Klingon purity and after peace was only secured through the most improbable means, they doubled down on the ban. Una's revelation provided a perfect opportunity to signal to the Klingons that they were serious about the ban -- hence why they would add the charges of sedition, perhaps. Ultimately, an infinitely long speech and the prospect of losing one of their best captains combined to make them find a loophole -- but not to invalidate the ban or call it into question. This Klingon context is why April, who we know is caught up in war planning of various kinds, is so passionate that the ban exists "to prevent genocide" -- he's not thinking of people like Una, he's thinking of the near-genocide they suffered at the hands of the Klingons.
This theory still doesn't paint the Federation in a positive light, since they have effectively invented a false propaganda story to defend a policy that has led to demonstrable harm. But it makes a little more sense, at least to me. What do you think?
It is how portions of the Deaf community have described it. For example, some portions believed that by giving deaf children cochlear implants, and through them, the ability to hear, they would be removed from the Deaf community, which they could consider genocide (see definition 2 quoted replies below).
That article isn't the only one that mentions that, either. There are others, both in the form of blog posts, or research article.
It may surprise you to know that neither Hitler, nor Stalin actually supported religion at all (and is probably where the contemporary US attitude of "we're proud Christian Americans instead of those communist atheists" comes from, but I digress.
For Nazi Germany, the murder was a more convenient way of achieving their goal of elevating Germans through eugenics by eliminating "undesirables", but they did also sterilise them too.
For Stalin's USSR, they also exiled people in addition to executing them. I can't say why, but I imagine it was also a matter of convenience compared to exile.
Genocide need not involve murder. You can also have a cultural genocide, where you aren't trying to erase a peoples by killing them all, but using other means, such as forcing them to lose their language/heritage, or taking away their children. Australia did that back in the colonial days, and it would be difficult to argue that it was not an attempt at genocide.
You do make good points, since the line that's typically drawn in medicine is one of quality of life. If a patient's quality of life is impacted by their disability, then it would make sense to offer the option of a treatment.