I’m guessing that it’s just something that Jiwoo developed living as a normie but also as a son of an awakened.
I think head of the family usually teach their force control to their offsprings when they’re really young so that power is what they always end up developing in the long run and end up becoming their own as they practice it repeatedly and grow older.
But having the power pass down since birth is definitely a higher chance. Jiwoo seems to be a special case from the very beginning, and he is also a genius and really gifted. if Jiwoo is really part of the Patrick’s family, maybe his shadow abilities is currently dormant

So… what if Jiwoo’s mom is actually a lover of Grandpa Patrick’s son. Then the main reason why Jiwoo’s mom made jiwoo live like a normie is so that the Patrick family won’t ever find out about him? I don’t remember who’s older between ian and jiwoo but The “Son”,ian’s dad could be from an arranged marriage, loveless marriage, which is why The loser turned out like that. And then u know, maybe about a year or two, their dad fell in love with Jiwoo’s mom, jiwoo was created and then the dad died. Jiwoos mom got maternity leave to raise jiwoo for awhile, and then whenever she gets a chance, she’s looking for clues on who killed “jiwoo’s” father