as selfmate said, double digits is a good age.
i'm a centrist and this is a topic i'm iffy on in certain places. while i don't necessarily believe it should be "taught" (because there are many different ways of construing this stuff, esp at a young age), i think that schools should have better resources and someone professionally equipped to handle questions about gender and sexuality. idk why people haven't come up with this idea yet, both "sides" win.