A great example of this strange recurrence is sex. In the past sex was a taboo subject worldwide simply because a lot of religions made it so. Religion feeds directly into culture and culture persists today, even for those who don’t consider themselves religious. In a lot of the developed world sex is becoming more talked about. Kids are talking to their parents about it with only minimal levels of discomfort, there are classes taught in schools on it and of course the internet has opened many doors (some horrifying). We’re getting there but we’re not there yet, a decade or two more and people will feel comfortable discussing sex fully. This is important due to all the dangers which are now associated with sex, STDs being the main ones.
In less developed or more religiously dominated countries this simply isn’t the case. Children feel intimidated or embarrassed to discuss sex openly. In many cases they’d face condemnation if they did bring it up. This too is changing but much less quickly than in the more developed world. The fact is that sexually transmitted diseases exist more prominently in countries with a lower GDP and understanding them is a big part of avoiding them. Educating the children in these countries would be a massive first step towards countering what is becoming a global problem.