Conjoined ( Siamese) twins are normally the same gender- either boys or girls. as far as is known a mixed-gender- one boy and one girl Siamese pair does not exist, nor does a duo of hermaphrodites...
Chang and Eng Bunker ( as I recall, no relation to Archie) were the first pair to survive to adulthood and they hailed from Siam. (they were male) hence the name. It is a congenital anomality and is...