yeah he did but 1 they arent blood related so the legit meaning of incest doesnt apply
2 the twins never treated the uke like a brother, it clicked for them when they were young that the uke was theirs as a partner for life, for the ukes perspective you could say he saw them as brothers but in ep 2 he said “omegas sometimes get adopted as partners for alpha children” so he probably just saw them as little kids he needed to take care of rather than as brothers, he also referred to the twins as “the kids” when talking to his adoptive parents which made me think of my previous statement, so familial bond incest doesnt apply
3 overall it would fall under pseudo incest simply because of their family book relation and not actual incest of any sort
No matter how hard you explain it's still incest, calling it pseudo incest just makes it clear that the story still takes part in a subgenre of incest. there is no ”legit” meaning that says that only blood related relationships can be called incest but what you prolly meant was its scientific/biological definition, saying legit sounds like you're basing on legal facts. I'm actually making this longer just because I appreciate your explanation. I'm just here for the thrill, so don't get me wrong
Ppl usually say it’s incest either way. Especially if they are adopted and grew up together as family.
It’s like how people call stepmom x (non blood child) incest because they still grew up as family.
In Japanese they have a separate word just for than but in English, all of it falls under the umbrella of incest.

author-nim really wanted to make threesome plus incest after Minty Fresh and Hyung's Omega huh