How to introduce a complicated family in Korean
I know the basics of introducing who is in my family, but I have a complicated family history and I don't know how to express that. In particular, I want to know how to say:1) I have a stepmom because I don't know my real mother.2) One of my younger brothers has a different father than me.3) My younger brother and younger sister has a different mother than me.

Question

Answer

I have a stepmom because I don't know my real mother.
저는 새엄마가 있어요. 친엄마가 누구인지 몰라요.

One of my younger brothers has a different father than me.
제 남동생중 한명은 아빠가 다른 동생이에요.

My younger brother and younger sister has a different mother than me.
제 남동생과 여동생은 엄마가 다른 동생이에요.
제 남동생과 여동생은 다른 엄마한테서 태어났어요.

Answer

step mother:새어머니 or 새엄마(계모)
different father younger brother
이부형제(이부동생)
different mother younger brother and sister 이모형제(이모aunt와 한자가 다름)
but we never say like 이모형제 or 이부형제 we combine them as '이복형제' and say 이복형제 in general