he was actually 20-21 when he gave birth to byul but still that was super young and I’m not sure how the author will write this situation…
He was 20 and that was according to old Korean age system. That means he was 18 or 19 at most.
And he was likely 20 only to avoid underage sex, which can be a nono with publishers, he's drawn and looks more like 12, even now, when he's supposed to be mid 30ties (and even his teen son look older than him), so it looks like the author wanted to make him as young as it is acceptable.
since byul wants to act like a know-it-all, someone please tell him that his dad is a rapist as well who baby trapped a newly awakened omega who was forced to carry a baby to term and birth said baby at 18 YEARS OLD. AND NOW YOU WANNA SIDE WITH YOUR FUCK ASS GRANDMA AND FOLLOW YOUR FUCK ASS DAD’S FOOTSTEPS IN HARBORING A RELATIONSHIP WITH HER? don’t make me laugh lil boy