Riddle: You give someone a dollar. You are this person’s brother, but the person is not your brother. How can that be?
It is a pretty simple riddle that does not puzzle your brain. Members of a core family are parents and children. Imagine that you are one of the children in the family and you give someone a dollar. The riddle says you are the brother of this person.
If the person you have given a dollar is one of your siblings, it is either your brother or your sister. As it is mentioned in the riddle that this person is not your brother, then it is your sister, obviously. The answer of this riddle is that it is your sister.
Answer: It’s your sister!