That sounds common-sense to me, but it seems un-meritocratic to assume it a priori.
That said, age matters. Very, very few people can start programming at 18 and progress to the top 20% of the field. I can't think of anyone who's done so, though I'm sure there are exceptions.
I didn't "program" either before 18, since I grew up in a household (and part of the country) without any access to computers. But I was indeed drawn to it young, and "learned to program" by reading magazines and sending off for free vendor literature (which did indeed have lots of nuggets of knowledge about all things tech).
Not saying its good, just it may be a resource management issue