Hey there!
Well, I'm 20 and have been playing violin most of my life. I teach students of all ages, and have a couple of adult students (in their 40's!) who have started violin lessons with me. Obviously when you are younger it is easier to pick up on things, but when you are older it is easier to focus on practicing. I would say to go for it, and who cares what your friends say? You might find that you take to it really easily! At first it will be frustrating because of coordination and all of that . . . but keep practicing and going to lessons and you will get the hang of it!
