Ok, I'll help bump your average up (but just a little). I'm 42, started building when I was pretty young, maybe 6, we moved when I was 10 and I had definately been building at least 2 years by that point. I built pretty regularly until about 9th grade (14-15?), I didn't quit at that point but definately slowed down since most of my model building friends either moved away or quit building which took some of the fun out of it. I had a sharp decline in my late teens early 20s. My last serious effort was in 1991 / 92 when I did an Abrams and Bradley (inspired by Desert Storm). I had a few false starts between then and 2002, but they were largely buy a model and some paint, then put them in a box and forget about them. In 2002 I found out some co-workers were building models and discovered the internet revolution (modelling websites) and I've been going wild since then. Its sort of funny modeling is largely a solitary activity but it is more fun when there is a group of people to share the hobby with.
My dad has been a big supporter of the hobby teaching me techniques and getting me kits when I was a kid, and even going so far as paying me to build stuff for him when I was a teenager (keeping me involved in the hobby and giving him an excuse to give me some spending money). In a kind of neat turn around last year I taught him how to resin cast. He likes to scratchbuild 1/1200 scale ships, now he can cast hulls, and common parts giving him more time to build up his fleets, and modify the similar but different ships of a class.
I have a 9 year old son, who dables in models. We've done a few of the Lindberg Dinosaurs, and some snap kit cars and airplanes.
Life lesson, I don't know how about don't dismiss all those old kits out there from Monogram, Airfix, Matchbox etc. In the past year I've rediscovered the simple fun of these kits, yeah they are not as detailed as newer kits but they are cheap and they actually get finished. When they are sitting on a shelf it is not that easy to tell them apart from a "better quality" modern kit that cost 3-10x as much.