Digg was the site that originally popularized up-votes and down-votes that are so typical on online posts today.
No. Slashdot was doing that, and was popular before Digg launched. Reddit also launched before Digg was popular, about 6 months after Digg did.
Meanwhile, algorithms that ranked content based on user votes were taking over all the web 2.0 darlings, including Flickr's "interestingness" ranking system, by the mid 2000's. Even outside of ordering comment threads, silicon valley was enamored with the idea of crowdsourcing indicators of popularity, and building algorithms around star ratings (including offline stuff like Netflix's DVD by mail, OkCupid's matching ratings for online dating, etc.)
I see Digg's use of voting as merely reflective of the overall trends in the mid-2000's. They certainly didn't invent it.
David Epstein's The Sports Gene talks about several areas where it's a feedback loop between nature and nurture:
But outside of all of that, it also matters whether we're talking about becoming a world class athlete or just a hobbyist. For weekend warriors running a 5k in a pack of thousands of participants who paid to be there, practice and training are going to be far more important predictors of their performance than any kind of genetic or innate talent. The genetic or innate bottlenecks might show up in the Olympics, but not the amateur hobbyist runners.