This is by no means scientific, but I took the ages in a few of the linked threads and averaged them and came up with 27.1 years old. That was from a sample size of 136 guys responding. I added one year to the ages of the guys who responded to the older thread (circa 2005). That's a bit arbitrary, and I could easily have added two years, but some guys responded to both threads and adding the one year from the older one seemed accurate enough.
So there's your answer. Sort of.