Early coding gives you a head start, but in my experience, things start to even out when everyone reaches their late 20s. I see a lot of developers who started young basically lose interest in learning new technologies by the time they reach 30; after 15-19 years of 'coding'.
I'd argue if you're willing to embrace a complex new skill in adulthood, you're probably going to be more willing to learn new stuff as your career progresses. This will give you an edge when your peers start getting set in their ways.
Another thing: I learned to code when I was 13, and was fortunate enough to have some friends in grades 7-12 who did the same, but ultimately the stuff we did was simplistic and hacky. It was totally undisciplined, and wasn't exactly production quality stuff. We were juvenile, and our code was juvenile. In a good way.
Fifteen years of coding? He he. These are just babies. Just started learning how not to over-design things.
And in reality years of coding doesn't matter. Learning to code early doesn't matter. What matters is with how many people you've collaborated. And how many releases of different products you've shipped.
You can code you whole life, but if it is the same damn piece of code, you wouldn't learn a thing. And if you don't actually release stuff, you also wouldn't learn a thing.
Last point (releasing stuff) is very important. If a kid 'learns' to code, but doesn't release his stuff - it is not real. Most of that learning is far from reality and wasted.
I know how you feel... I didn't start until I was 21 and I'm 25 now. If you try to compete with somebody who has been coding since they were 10 on pure coding talent you'll lose.
But that's fine. Use your cross-functional skills to your advantage... whatever you did from ages 8-21 when combined with the coding you did from 21-present is likely just as (if not more) valuable than the skills a person who's been coding since childhood.
As someone who has worked with many different programmers from very different walks of life, it doesn't matter. Some of the worst programmers I know started early. Some of the best started even later than you.
It all comes down to your ability for self inflection, a strong desire to always be better and, of course, a love of programming.
Don't worry. I suspect the reason that people percieve that most good coders started young is that people who start young have already demonstrated that they have a lot of interest and passion in the subject. So it follows that they would be good disprortionantly often.
If you have the same passion, then starting late shouldn't hold you back that much.
Having said that, I am one of the lucky ones who started young.
As someone who started programming when I was 21, I sometimes feel like I don't stand a chance.