A young man excitedly tells his mother he's fallen in love and that he is going to get married. He says, "Just for fun, Ma, I'm going to bring over 3 women and you try and guess which one I'm going to marry." The mother agrees.
The next day, he brings three beautiful women into the house and sits them down on the couch and they chat for a while.
He then says, "Okay, Ma, guess which one I'm going to marry."
She immediately replies, "The one on the right."
''That's amazing, Ma. You're right. How did you know?"
One day a girl brings home her boyfriend and tells her father she wants to marry him. After talking to him for while, he tells his daughter she can't do it because he is her half brother.
The same problem happens again four more times! The girl starts to get pissed off.
She goes to her mom and says: "Mom what have you been doing all your life time? Dad has been going around laying every maiden in the town and now I can't marry any of the five guys I like because they have turned out to be my half brothers!"
Her mom replies: "Don't worry darling, you can marry any one of them you want, he isn't really your dad!"