Adolescence may last 10 years.
..and even longer for some. I'm enjoying reading articles like this with two girls so close to 13. I've seen and lived it as a parent and step parent before and find each kid has different manifestations of adolescence and each kid has a different time period of growing up but all kids go through it for some period of time.
"In short, an adolescent's weakness is other adolescents. And we're not just talking about peer pressure. The mere presence of peers makes them less cautious."
The Teenage Brain: Spock Vs. Captain Kirk : NPR Ed : NPR