At what age are you capable of making life altering decisions?

My oldest son, who is now 17, called/text me last night requesting that I sign papers for him to join the Army. He lives with his dad now, has for a couple of years. I refused. I refused for the following reasons:

• He is still in High School and won't graduate till next year. Why sign? Why not wait till he is 18.
• A lot of things can happen within a year. I don't want him to commit to something this huge without fully understand the potential consequences.
• He just started driving. He isn't mature enough to make this decision yet.
• I want him to really weigh his options, with college or trade school before deciding on the military.
• and finally... just because I don't want to lose him to the wars of this world.

I have read that we should let teenagers make their own decisions. What kind of decisions are we talking about here? What kind of clothes they can wear? What friends they associate themselves with? Whether or not to join the military at the tender age of 18? Do these kids know that's joining any branch of the service is the 'real deal' and not a video game? You don't get to reboot and get 'new lives'.

When you are young you make emotional decisions and not rational/intellectual decisions. I've also  read that the average human brain isn't fully matured till the age of 25.


 25!!!!

 Today, I'm 38 years old, a little more comfortable in my decision making process, but I still stumble. Constantly questioning if I'm doing the right thing. These days my decisions are less emotional and a little more rational/intellectual.

So I ask you, at what age are you capable of making life altering decisions?