I think it’s heavily implied that he’s not adopted. Why else would the fuckass brother react so dramatically to her mother’s answer? He would’ve probably been over the moon if Dojun was actually adopted. He also keeps saying that they’re brothers in the end, even saying that they would be lovers if they weren’t brothers. But honestly, even if Dojun was adopted it wouldn’t change shit. It’s still incest even if they aren’t blood related.

Wait so is Dojun adopted? Or is that ugly hoe of an alpha brother just being delulu to justify his incestuous obsession with his own brother