A "Proof"

We now take a break from our regular scheduled posting to post a "proof" of sorts. Why in quotes? Because it HAS to be flawed. I'm not so deluded to suppose that I've thought of something no one else has.

given: "man" A, "woman" B, "sex" C, "are married to one another" D, "ethical" E and the statement: if A and B and D then C = E

Also given: , "intersex" Y, Y=A, Y=B

Suppose: if A and A and D then C is not E. A and A and D = A and Y and D by substitution; A and Y and D = A and B and D also by substitution; finally C=E by way of modus ponens. Our logical supposition was that C is not E, therefore the statement is false and hence ethical sex is not predicated upon two people of opposite sex being married to one another.

Thing is, that the only way I can see to disprove this is to make intersex a separate gender. However, this is something I could not find support for among conservative Christians, quite the opposite seems to be the case. Still, somehow you need to be able to remove the relationships Y=A, Y=B, but all the reading I have found on the subject is that the word "intersex" is used precisely to more accurately expose those two relationships. The following is from Focus on the Family's:

Technically, the term hermaphrodite, with its origins in Greek mythology, speaks to someone who is half-male and half-female. In this strict sense, a hermaphrodite is not synonymous with someone who is intersexual.

Anyone? Anyone? Beuler?