I think you're right but Sungho probably didn't care. He probably thought 'I have family now'. Hopefully we get more backstory about his past! There's probably more than what meets the eye.
As far as I remember he's the biological father although you're right he would probably need a dna test to be sure. I don't think this author will put us through the angst of "this is not his bio baby" or even "the baby meets its bio mother". At least I hope so
Yea after I read some more its looking like he is the father, but the timing is a bit off. Regardless he is the father now whether its biological or not. I just hope the mom doesnt come back and try to take her away ╥﹏╥
Wait I just started rereading and I just realized that his ex of OVER A YEAR AGO left him the newborn baby. Which means it cant be his biological baby. Im shooketh...how did i miss this.. or am I wrong??