Not that we know of

My older sister and I look very similar. We were in a hostel in Shanghai when we walked past two men, one of whom called out to us "Excuse me, are you twins?" We said no, sisters but not twins. The man asked us again, "No, you are twins aren't you?" We said no once more, and carried on downstairs. "Are you sure?" he said. "Yes we're sure!" said my sister.  

We could hear him say to his friend as we descended, "They are definitely twins."