An Unfaithful Father

SON: Daddy, I fell in love and want to date this
awesome girl!
FATHER : That's great son. Who is she?
SON : It's Sandra, the neighbor's daughter
FATHER : Ohhh! I wish you hadn't said that. I have to tell u something son, but you must promise not to tell your mother. Sandra is actually your sister.

The boy naturally bummed out, but a couple of months later
SON: Daddy, I fell in love again and she is even hotter!
FATHER: That's great son. Who is she?
SON: It's Angela, the other neighbor's daughter.
FATHER: Ohhhh! I wish you hadn't said that. Angela is also your sister.

This went on couple of times and the son was so mad, he went straight to his mother
SON: Mum I am so mad at dad! I fell in love with six girls but, I can't date any of them because daddy is their father!

The mother hugs him affectionately
MOTHER: My love, you can date whoever you want. Don't listen to him. He isn't your father.