Sex at a Young Age

I was browsing some posts and people are writing that teens/children are having sex younger and younger. Yes, I do agree. But I was thinking not that long ago, people married their children off when they are at a really young age. So what I was thinking is why are people are freaking out about people having sex?? It's not like it was not done before. So is it parents over protecting children and our society is trying to push them into having sex (ie. music videos, advertisements, etc.)? Or is it our society have evolved and we do not tolerate it anymore?

Feel free to express your opinion..