On Generalizing Twins

Have you seen the Siamese twin sisters? They are exactly alike. This was told to me by most non-thinking cousin, we call him Ike. Do they have the same sister? I asked him, making him think His brown amber eyes began to cross, and his face got all pink. Were they born exactly the same moment? I asked this little creep. He found their birth certificates, and I swear I heard his brain squeak. Are they in the same class? I asked, for I knew they were not. He refused to relent his original theory, he rarely has a smart thought.