Well, there's always the fact that we don't "know" that any of that's true yet in the current version, but that's semantics...
We've learned from past stories that Winathians regard solo children as freaks, shun or taunt them. How enlightened is that?
Nope...not very enlightened, but very realistic. Very human. How many people to this day treat other people as "freaks" for reasons that most of us consider "unenlightened"?
Perhaps Mekt's parents were negligent. They could have lobbied for equal treatment for solo children, formed a Parents of Solos support group, fought to reduce prejudice or formed a community of parents with solo (or mixed solo and twin) offspring.
I don't know about "negligent"...or at least deliberate negligence. In the Reboot, Kirth and Dalya Ranzz were hardworking farmers. Maybe they were too busy to give it much thought; it was just "the way it is".
It is an interesting question, though--the Winathians are otherwise portrayed as some of the most free-spirted and open-minded people in the UP. And I don't remember any signs of Garth being stigmatized for marrying some "off-world Solo" or somesuch...