When it comes to thinking up new ideas upon which to found a business, and having the skills to turn a startup into a success, men and women begin on a level playing field. But in practice, men still heavily outnumber women in the high-risk world of entrepreneurship and venture-capital backed startups. Which leads to the obvious question: Why? The answer, says Wharton management professor Ethan Mollick, is multifaceted, but at its core can be traced to a few fairly simple points of personality and gender tendency on the one hand, and the broadly human tendency for birds of a proverbial feather to flock together on the other.…