
I'm re-reading because I stopped somewhere in the side stories and not don't remember a lot, I thought there was a plot in them somewhere about Jae-In thinking their kid might have been fathered by the rapey antagonist, I was just wondering if the figured out for sure that it wasn't him? Or did that just kind of trail off

There could be potentially a 50/50% of possibility of postive paternal result if fathers are sharing same DNA. Just like when in reality lost families can identify relations on either which parent, siblings, and cousins are tested. Since this is omegaverse I think the author used the notion of jaeshin carrying taeyoons child because of pheromone compatibility, an omega needs the pheromones of the one who impregnated him so he can have a stable pregnancy.
Did Jae-In and Taeyoon ever figure out for sure if their kid was fathered by Taeyoon or Director Jeong-hyuk Choi during the SA?