Q. How should a child be taught subjects of a sexual nature? How should he / she be informed of prohibited and permissible acts, about masturbation, zina, etc.? What age would be proper to teach them about these issues?
A. Western influence has prompted you to ask this question. The western kuffaar are immorally obsessed with sex, hence they satanically fabricate sex ‘education’ for children.
How did you gain knowledge of these sexual issues? How did the millions and billions of children from the time of Nabi Aadam (Alayhis salaam) acquire this knowledge? In the same way as you and us all acquired this knowledge, so too will all other children until the Day of Qiyaamah acquire it. Do not burden your brains with copro-stupidities.