In the fundamentalist conservative mindset, being aware of potential differences means being tempted by those differences.
Fundies believe that homosexuality or transgenderism is a matter of choice because everyone is born "normal", not gay or trans. Those deviations are deliberately chosen by sinful perverts for evil purposes, such as molesting children.
If kids learn about these sins, they might (a) not be properly horrified by them, (b) ignorantly trust such evil adults, and (c) be desensitized enough to experiment with such perversions themselves.
The only way to keep kids from becoming gay or trans is to keep them in a state of {holy} innocence i.e. complete ignorance. The fact that this doesn't work has yet to penetrate the bigot mindset.