Funnily enough there arent many sicentific studies on the effect of steroids in teens, maybe scientists are reluctant to use humans as ginnea pigs which is essientially what you become when you take steroids at a young age. Since little scientific research exists i will attempt to address the using common sense and basic biology.
In your teens your hormone levels are not nearly as stable as those of an adult male, acne, depression and pubescant gyno are indicators of this. It does not take a genius to understand that steroids could exascerbate this instabiltiy. An unbalance of hormones has many negatives including gyno, lethargy and depression. Severe depression is well documented in teen steroid users (
http://www.msnbc.msn.com/id/6700913/site/newsweek/).
Under-developement in teens is not just physical its also mental, until you've used a substance you don't know how your body is goin to react to it. If your cycle goes well then great but if things start to go wrong then you have to deal with it. Most hormones are regulated by negative feedback loops, unlike some drugs where cessation will end the negative sides, cessation of a cycle is not usually enough to end the negatives. It often requires positive action on the part of the user to bring the body back to normal. Personally in my teens i was not nearly as mentally equiped to deal with problems as i am now.
When you consider that levels of total testosterone in males aged 17-18 is 300-1200 ng/dl compared with 300-950 ng/dl for males aged 19-40 is it really worth turning to hormones when you already have the edge on most of us.
At the end of the day the decision is up to you. Personally the potiential negatives versus the potiential positives wouldn't warrant the risk.
Just my 2pence