Should parents get worried if their 15th years old teens commit sex?

OK we know that sex at teens is part of nowadays popular culture but still,as a parent we should concern about everything that happen to our child. I heard many news and other contribution made and support by our government about sex at teen stages and they said it’s inappropriate,unnecessary for teens,and of course it’s morally wrong. Other theory shows that only parents with daughter will concern about this lifestyle.

As a good parent should we really concern about this lifestyle? Would it be wrong to allow our teens to experience sex at early age? Then what will you do as good parent toward this issue?