"on the job"? Most likely. But I spent a lot of time and money getting a degree from an accredited university, where I was bored the whole time and maxing out the number of credit hours they would let me take while also working as much as I could. Why? Because I could've aced the first 2 years of CS classes by the time I was 13. I would imagine that's not uncommon among people who grew up with a hacker mindset and had the resources to explore it. I surely had gaps in my knowledge - not saying I didn't learn anything from the college experience. But I would love to live in a world where I didn't feel like I would, at some point, be better off with an accredited 4-year degree just to get or keep a job in the first place.

13 seems low, but I had 3 years of full time programming experience by the time I was 17.

It's really important to note that I'm not particularly gifted. I was required to work "real jobs" over the summer starting at 15 and the only way to convince my parents that programming was a "real job" was to make as much as I could working at the community pool. After the first summer I kept working over the semesters nearly full time. I was doing freelance Perl CGI and PHP+HTML+JS junk. my main advantages were:

1) I could do piece work for $8/hr,

(2) I presented professionally because I was usually the only native English speaker bidding on the project,

(3) I was a single person doing full stack + sales/bidding (the competing offshore outfits mostly sliced up labor between backend, frontend, and sales due to language barriers and extremely low-skilled programming labor. For projects of the size I was bidding on this introduced a lot of expenses/overhead without any real advantages), and

(4) I was available in US time zones when bidding on these projects. Even during the school year my after-school availability was way better than the offshore shops could usually offer, and I could answer emails during the school day.

To reiterate: not a genius! Just a kid slinging super simple HTML+JS+SQL+PHP/Perl. I didn't even know SQL for real; I knew CREATE, SELECT (without joins), UPDATE, INSERT, and DELETE. Joins were implemented using multiple queries and for loops. Didn't matter for my clients, who just wanted cheap CMSes/ordering systems/etc. for random folks' .com get rich quick schemes, pizza shops who thought they really needed a customer website, etc. I'm pretty sure grubhub/slice/google maps/social media destroyed my old market a decade ago ;)

So a real genius getting there by 13 seems like an extreme outlier but not at all impossible.