Why does the president bitch hate Jiwon? I dont get it (￣∇￣")

So I think he’s the son of a son that she has. Her son (or even daughter) could have been a problem child, got into trouble and then Jiwon was sent to love with the president (grandma). Or Jiwon is an illegitimate grandchild. Those are my two theories

I thought too that he is illegitimate, but i think it isn't a reason to be hateful with him. She's really on my nerves. I could ask why is she like Suha that much ╮(￣▽￣)╭ Actually i like Jiwoon more than Suha. And that menstruationhead fucker....why wasn't Sangwoo written into this manhwa ╥﹏╥