Mechanics-wise, younger players will always have the upper hand. Reaction time means a lot in fast-paced games such as DotA, and older players just can't keep up.

As for in-game decision-making, experience is everything, and age means nothing. I have a friend who's only 15 this year, but he's been playing with me since he was 6. Technically, we share an equal amount of non-competitive experience, which makes him the better player if he chooses to move up to compies.

His brothers and I both played in the same clan, so he used to watch them play. He started playing soon after. He didn't move on to D2 though, he switched to HoN when it came out.

Doesn't matter. No need to rehash old stories when they serve no purpose.