I think your average age for HN is off by 5-6 years. Atleast that is my impression from the comment quality and the recent poll:

  Age     Votes
  -------------
  0-10       65
  11-15      42
  16-20     552
  21-25    2030
  26-30    2400
  31-35    1532
  36-40     735
  41-45     359
  46-50     148
  51-55      84
  56-60      44
  61+        52

https://news.ycombinator.com/item?id=6058598