No two are the same, but generally a good sign is if they have outlier behavior in their past. For example, if you won a gold medal in the Olympics, there's a good chance that you would at least get an interview -- the level of determination and persistence required to accomplish something like that would definitely be helpful in founding a startup. (that said, I don't know that we've ever actually funded an Olympian) A more common example would be creating a popular open source project (e.g. the creator of Sails.js is in the current batch).