One thing I can say for sure about this.
My sweating also came around 12-13 years old.And when U are at this age,U sweat less.
So what I am trying to say,even then we sweat in our hands and feet?.
Something is wrong,HH is a diseas.We sweat when its not nessesary.Its the fight or fligt system that we develop when dinosaurs lived on our planet.
So normal persons can say

mg, I almost crashed my car today,and I was so scared that I got clammy in my hands.This is perfectly normal.
But we sweat for no reason/explenation, so something is wrong.Biological,nervesystem etc.?
Think that when we where 12-13 our sweatglands under the armpits was not developed at that age.But when we get past the puberty,then it is.And some get HH there to.
I consider myself lucky,because my mainly problem is hands/feet,but yes I can also have sweat attacks under my arms,back,groin,face,even my ass!But I have uptil know been lucky whit that,not a big problem for me.
Before I use to think,God, why couldent I had HH in my armpits instead.Because I tought that armpits was easier to treat,more options.When reading about people who got this shit all over.Hands/feet,face,cranial,groin,back,ass,knees,armpits etc,and its severe all over.Jeeeeeez I feel sorry for those people,and can actualy understand an ETS-operation.And hoping for that the trade off whit one devil to another can be better.Even if I am personaly against ETS.Because its a trade off!!