simple IQ question

I read about this from the newspaper, publishing a content from a blogger's posting. So, I excerpted the question here, cos I got it wrong the first time, the same with one of my colleague "p

"He is not your brother, but he is your father's son. So who is he?"

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answer is "you yourself lor" *_*

for girls, the question should be rephrased to

"She is not your sister, but she is your mother's daughter. So who is she?" lor...

If you get it right in your first try, very obvious you are clever than me lor *_*