First of all this is a great topic to do a report on...though this probably doesn't help, I think assigning a specific age capable of bearing the emotional baggage of sex is a little vague. Sure, you COULD really have the maturity required, but then again you still might not. Sex is more than reproduction( duh
) and more than pleasure. Sex is emotionally demanding. I think age isn't the domineering factor, it's relationship. If that SOLID foundation isn't there, you'll crumble under the weight of the resulting load. There's a "promise" in sex and I think that sometimes we find it hard to try and fulfill someone else's needs before our own (which could go back to age...). Overall, I'd have to say the strength (longevity...) of the couple's relationship is of the utmost importance.
I hoped I helped you.