Anecdotal, and I think expanding on the "portal" idea, I've just downloaded MAME + GENS for my two (young) boys (2 hours ago). The timing of this article is relevant for me.

Metal Slug, SF2, Sonic, Lion King, Toe Jam, Earth Worm, these were the first games I ever really played as a kid for me were my own portal to gaming which expanded into an early career at Uni although now it's only recreational, I can't help but think I enjoyed the gaming when I was 10 years old, than I do now.