They first work to get your kids to not listen to you, or rather to make the teacher the sole arbitrator of information. How do they do that? By telling your kids that you are old-fashioned and your advice is "outmoded." This works to separate your children from you, especially if your kids have problems. Their tactic works best if there is dissension, divorce or no communication in the family.
Their goal is to successfully disengage your children from you.
Sex ed is just the mode by which they do it.
“When a man says to me ‘’I will not come over to your side ‘’, I say “Who are you? You are no one. We already have your children’’.- Adolph Hitler.