The dialogue established that they were divided into Illyrians who gave up genetic manipulation and Illyrians who still practised it. They're all still Illyrians which is why it's odd that Starfleet Medical never noticed before.
I was distracted, paying less than perfect attention, so I've had to amend myself a couple times... But there's a couple holes in her story.
1. She is not human and does not look like what we think Illyrians looks like, although I suspect the Ilyrians from Enterprise were modified for space travel, rather than dedicating more power to the deflector shields, or building better deflector shields.
2. Her colony was inducted into the Federation as a colony world, and not a member world, which means that it did not get a vote on the Federation Council, and a hundred million mostly human colonists probably showed up to colonise the colony once it was formally admitted, displacing the original colonsts and their culture.
3. I think the Ilyrians changed their name when they gave up gene modifying, which is how she was so vague about who the not Ilyerians are who got half the planet, when her lot were definitely still the formerly dominant species on that planet.
4. Why would a bunch of aliens who were Ilyerians one or two generations ago, use human slurs that would offend their own grandparents?
5. Did the new Federation Colonists outnumber the semi-native population by double or triple, which is why they were able to impress their value system on the Ilyrians and the not Ilyrians anymores, after forcing a foreign legal code on them
6. Was Una trying to pass for human when she joined Starfleet, or was she trying to pass for an Ilyrian, who had renamed their species, and given up genetic modifications? Politically different, genetically the same.
