Most Helpful Girl
I believe parents should have their children make their own descisions. That could start with something simple like picking a toy or what meal they want in a restaurant (also decisions!) and eventually what sport they'd like to play, which school (middle or high) they'd like to go to etc.
I believe in a loose way of raising. Strict parents only create sneaky children. (I'm the example of it, sneaking out and lying to my parents when they disagree with something I want to do even though it's safe) so I think teens should start early making decisions so they know to turn to you for advice and guidance. So they know they can talk to you without you forbidding them anything. They'll make their own mistakes and learn that way.2
Most Helpful Guy
That should depend on the type of decision but as a general rule, self-responsiblity should be taught from early childhood onwards. The more you teach a child to be mature and act in a responsible way, the less trouble it will later give you.
Unfortunately, America has a culture of helicopter authorities where parents and teachers mistake themselves for police officers and treat teenagers like stupid 5-year olds. In fact, it's the exact opposite way. If they raised them in a loser way like parents and teachers do in Europe, the teenagers would also act more maturely. How are you supposed to make responsible decisions if you've been treated like a mentally disabled person for your whole childhood/puberty?1