A mental patient
A physician visited a California mental institution and asked a patient "How did you get here? What is the nature of your illness?"
He got this reply.
"It started when I got married and I guess I should never have done it. I got hitched to a widow with a grown daughter who then became my stepdaughter.
"My Daddy came to visit us, fell in love with my lovely stepdaughter, then married her. And so my stepdaughter was now my stepmother."
"Soon my wife had a son who was, of course, my daddy's brother-in-law since he is the half-brother of my stepdaughter, who is now, of course, my daddy's wife. So as I told you, when stepdaughter married my daddy, she was at once, my stepmother. Now since my new son is brother to my stepmother, he also became my uncle.
"As you know, my wife is my step grand-mother since she is my stepmother's mother. (Don't forget that my stepmother is my stepdaughter.) Remember, too, that I am my wife's grandson.
"But hold on just a few minutes more. you see, since I'm married to my step grand-mother, I am not only the wife's grandson and her hubby, but I am also my own grandfather.
"Now can you understand how I got put in this place?"