Whole example is 반말체. So you should not use it to elder people In Korea most people use 반말체 to YOUR 누나 (Sister) Edit: A tense is wrong 아빠, 밥(을) 드셨어요? => 아빠, 밥 먹었어? (Tense fix, eliminate) Bonus 아버지, 진지 잡수셨어요? (Tense fix, more honorific than original) You can remove '을' from above sentence