A fair percentage of people who start developing software early end up being passed by people who started later. A seemingly large factor of this is kids learning bad habits on their own and not being able to correct them later, or having a much more difficult time correcting them. (I'm not saying that is the case here, just generally.)
Caveat: we're both dealing purely anecdotal evidence and a fair bit of conjecture. We could easily be wrong.
But I've also spent a lot of time correcting bad habits, reading on good habits, and relearning a lot of things I did as a child -- and most of the code I wrote as a child was pretty awful.
Still, it's something that I've heard often and I can understand the logic behind it.