Like the Horta?
I remember when the world’s first “test-tube baby” was born. It was a big freakin’ deal!
Nowadays… yawn. It’s almost common these days.
I imagine by the Star Trek era it’s nothing special at all. Which (fankwank!) is why it’s never mentioned on-screen by the characters - it’s so routine/common it’s not worth mentioning.
I remembered B’Elanna’s story incorrectly. I remembered her as being 3/4 Human and 1/4 Klingon.
No kill I
I want to see a hybrid human x kzin.
Even before that, there was Devinoni Ral in the TNG episode The Price — who explained to Troi that he’s so good a negotiator because, like her, he is “part Betazoid”: “my mother was one half, I am one quarter.”
If I recall correctly, the Kzin and the Humans share some kind of interstellar microbial ancestor - so this would also be doable. Assuming that ST Kzin have a similar backstory to KS Kzin.