I feel like that sperm donor think that jinhyeong's worth is 'his one and only son'. Maybe if he did have another siblings (brother especially), his father might have left him alone + neglected him wayyy more as a child.
I'm so sad for whoever kids born by that kind of parents..
All this for a so called useless and worthless son. He can't be that worthless if he's doing this goddamn much to get him back