21! I've had a lifelong fascination with herps, but just got my first one a month ago. I love being an adult now. It gives me the freedom to appease my childish desires.
I'm 29 and my girlfriend is 24. I have had geckos for the past 15 years though. I think most people who start in their teens will tend to keep the passion for these little guys!
Looking at the stats, even though they aren't statistical in the way polling companies are, and the poll isn't that broad, it seems to me that people of all ages tend to keep these lovely leos. : )