All you can do is reason from the scriptures (JW post on another site)
This defeatist mentality is at the root of the JW belief. Instead of thinking there is only one set of rules by which we must organize our lives it makes greater sense to take a leaf from reality and not run your life on hocus pocus from the ancient world.
We are born with undifferentiated sexual proclivities and usually early on, sometimes after a little experimentation we realize where our natural interests lie.
Homosexuality exists, not from choice or by design, it is simply a fact of mammalian life on Earth. Religious people fear things which do not accord with their childish concept of what an invisible spirit creator decreed, i.e God made man and woman and they had sex and the woman gave birth to children. No room for homosexuality or bi-sexuality there.
How crushing this must be for those of the minority who do not fit the Biblical prescriptions. How disgusting for Jehovah's Witnesses to blindly follow the Bible and each other in asserting their hurtful ignorance.