> Your posts are like a mine field that can explode at any moment.

:D LoL. Why would you think that? 

> I think that one has to consider the great variety of cultural sexual norms and behaviors across space and time.

Let me consider. I do not believe that pre-modern man thought primarily in theory about his sexuality and would boldly claim that pre-modern people had certain practices in common with regard to the manhood and womanhood of their adolescents. These in turn, I would agree, differed significantly from one another, which I attribute to factors such as climatic and geological conditions, i.e. the localities to which people were confined. 

Mountain peoples had different rituals to coastal peoples, nomads different to sedentary peoples, which I consider to be the greatest distinction in the lives of pre-modern people, since that was also their economies. Accordingly, their cultures formed around their living conditions. Some may have been more permissive than others, and again I see the climate as a major factor in this, not exclusively of course. In the tropics, nudity is normal, but not in cold climates, for example. Certain practices had to do with hygiene and/or which plants and animals people mainly came into contact with (though they may have attributed it to their Gods, as well). Where people lived in border areas with other foreigners, they influenced each other and so on.

> Engaging in sex and dealing with the consequences that go along with it is a life altering decision, especially for young ones.

Yeah, while that is the case, it need not sound like prison or a scary thing to face, for example. If you mean pregnancy and parenthood with long term consequences?

> ... so we're charting new territory as far as sexual development is concerned.

I find extending childhood extremely problematic. To give you the chain of my thoughts: When you raise kids by the practice that everything else but biology comes first, you end up with adults who are at high risk to stay in an infantile state of mind, since they were put in the situation to avoid the responsibility to lead a household, to manage finances or the numerous other tasks like taking care of other family members.

The extended childhood leads easily to a false sense of entitlement and to adults who then, well over their thirties and forties, still expect their parents/or government to take care of their needs (and demands).

... I would not call it "new territory" though, but a territory in danger of becoming too narrow and closed up. One, which will be avoided on top of what we already got, if you allow children and teens to not only delay puberty but make it impossible through puberty blockers and irreversible surgery. And to take only their own word for it. 

Let me ask you a question: When you were a kid and your parents said "no" to one of your whimsical desires, how do you judge it from your present perspective? 
My question of course implies that the desires of the pre-pubescent are *all* but mature, since the maturity to become aware of ones self centered desires, is to undergo puberty in full. So that at the end of that painful process you built up enough self esteem according to your man- or womanhood. The brain of the child and teenager is not fully developed, either. Would you give them the responsibility to decide what "social gender" they want to be? Adults, who think that way, are themselves stuck in immaturity, I suppose.

... I think I might know your overall position, please correct me if I am wrong. My man (who you resemble in my mind),  has the attitude to see the great picture and to have trust that things will balance them out. Still, you need something/someone to balance those things. While he is often enough right, he often enough is wrong in the detail (same counts vice versa). To spare the intimacies ;)