While I don't like the idea of incest and it seems to many (perhaps even to me) to be unnatural and wrong. Decriminalisation seems to be a sensible step and, just I would have supported decriminalisation of homosexuality in, whenever it went though, I should support decriminalisation of incest now.
It is common to hear politicians say, "What adults do, in the privacy of their own bedrooms, is not a matter for the state." If that's what we believe then that's what the statute book should say.
As for the idea of "freak children" this is not relevant for homosexual incest or, frankly, heterosexual incest between careful individuals.