A scientific definition of a hand would probably use the word 'typically', to encompass the exceptions. The human hand typically has five fingers, but you wouldn't say that someone with 2 fingers and a thumb doesn't have hands. The definition of hands includes those with polydactyly and those with oligodactyly. The idea that the definitons of female and male are biologically based and absolutely binary is silly. You're understanding of the definition of male and female is just limited, and when you encountered a case that didn't fit your definition, instead of expanding your definition to include these case you decided to deny the existence of those cases. It's like if you had the definition of hand as having five fingers and then when you came across a person with six fingers, or two, you decided to attack them as someone who doesn't have real hands.