I think this heavily depends. Sex education for a lot of places, especially in rural areas, tends to be fucked up backwards and downright harmful. Last I checked several states have abstinence only sex ed and do things like show kids a bunch of pictures of STDs and leverage scare tatics to deter them from having sex. I think opting out of that shit show and having a candid conversation with your kid about sex is probably the ethical thing to do in those places.