You’re probably just as quickly turned off by a legal-looking kid, when you learn their age, as I am.
The problem with being attracted to children, is being attracted to children. Not their child’s physique. Children have immature minds, even as their bodies can look adult.
By your logic, finding underage people attractive is fine, if they look like adults, because you think it’s about appearance, not how developed their minds are.
There are underage people who can be mistaken for adults, and there are adults who can be mistaken for underage. What matters, is what’s in their heads.
And like the other guy said, it’d be pretty fucking sad to be a young-looking person if the only people wanting to sleep with you were creepy pedos. Luckily, that’s not how it works.