They aren’t fit to become parents because they CAN’T become parents except through adoption or surrogacy or pre-gay heterosexual sex. They are NOT a natural family unit.
Indeed, it is in complete dishonor of the roles of man and woman from which they came from and to which they pretend to support. This is a complete fraud, like a pirate who steals a boat and then claims he was for free Carribean cruise business all along. Homosexuality fits in the communist Orwelianism of ends justifying the means.