I don't think that is correct. I'm not even sure how they would go about determining that since hacker news profiles do not include age information and the site does not use any form of analytics.
If the data source is doubleclick, how does it even know who's on HN?
I'm trying to figure out if this makes me (49yo) young-at-heart or just immature.
I don't think it reflects much on any members in particular. It's a site centered around Silicon Valley, which is an inordinately youth-obsessed culture.