The most obvious pleiotrope that I can think of associated with startups (possibly all businesses) is that CEOs tend to be, putting it bluntly, jerks.<p>The same qualities that make for a successful CEO -- ruthlessness, tenacity, the ability to play fast-and-loose with the facts when necessary -- also make for the kind of person you don't want to hang around with much. The better CEOs I've seen are able to compartmentalize this ability: they can be likeable, loyal friends, and restrict their ruthlessness to their business relationships. In the close-knit startup world, where the lines between business partners and friends blur, this is less practical.<p>I'm not saying I would change this -- I need a CEO who is ruthless -- but the side-effects are unfortunate.