In an election year, you will repeatedly hear politicians claim that showbiz is a hotbed of lefties.In one sense, they’re wrong: The conglomerates that own the studios and networks tend to be right-leaning. But in another sense, the leftie accusations are accurate: Showbiz is overrun with southpaws. If left-handed people comprise only 10% of the population, why were 50% of the Beatles left-handed (Paul McCartney, Ringo Starr)? And lefties are disproportionate in categories like execs (Jeffrey Katzenberg, Brad Grey, Oprah Winfrey, Bill Gates), filmmakers (James Cameron, Spike Lee, Ken Burns), top female stars (Angelina Jolie, Julia Roberts, Nicole Kidman, Jennifer Lawrence, Scarlett Johansson), and late-night comedy hosts (Jon Stewart, Jay Leno). The roster of southpaws is eclectic, including Matt Groening, Hugh Jackman, Patrick Whitesell, Julianne Moore, Matt Lauer, Adam Venit, Keanu Reeves, Morgan Freeman, Hilary Swank, Will Ferrell, Jerry Seinfeld, Sid Ganis, Steven Bochco, Lisa Kudrow, Henry Selick, Donald De Line, Eminem and Seth Rogen. So, is it safe to assume that left-handed people are more creative and somehow superior? We lefties would like you to believe that, but the rollcall also includes Billy the Kid, Jack the Ripper, John Dillinger and the Boston Strangler. Clearly, it’s not a matter of better or worse, just … different. Before he discovered his directing talents, John Madden was a thesp. He told me, “As an actor, I thought ‘Oh, no, this (career) won’t do for a left-handed person.’ Left-handed people are very aware of the whole, of the big picture.” The director of “Shakespeare in Love” and “The Best Exotic Marigold Hotel” (which had its world premiere in London this week) says he studied the connection between the brain and hands when working on Arthur Kopit’s play “Wings,” about a woman’s stroke and its aftermath. Right-handed people are controlled by the left hemisphere of the brain, which manages speech and logic — “crucial activities to get through life,” says Madden. Lefties, on the other hand, are ruled by the right hemisphere, “which has all the intuitive, whole, overview functions.” That might explain the number of performers who also work in other territories like writing and producing: Whoopi Goldberg, Tina Fey, Ben Stiller, Griffin Dunne, Tony Goldwyn, Emma Thompson, et al. And then there are nuances. Christopher Nolan told me he writes with his left hand, but brushes his teeth with his right. Ambidextrous? That term seems a little too prosaic for him. Like many of the other names here, the man behind “Inception,” “Memento” and the upcoming “The Dark Knight Rises” is clearly too original and creative to be confined by easy classifications. Five of the last six Presidents have been left-handed: Gerald Ford, Ronald Reagan, George Bush, Bill Clinton and now Barack Obama. The right-handed Commander in Chief: George W. Bush. (And, yes, politics counts as showbiz. And no, we won’t make a cheap joke at the expense of righties here.) Left-handed athletes? We don’t have space to get into that. The late, lamented list of southpaws include Cole Porter, Marilyn Monroe, Judy Garland, Kurt Cobain, Jimi Hendrix and two people who were key to the creation of showbiz as we know it: Thomas Edison and Charlie Chaplin. So are there disadvantages to being left-handed? In the book “Left-Hander Syndrome,” Stanley Coren cites medical studies saying lefties “seem to be more anxious about nearly everything,” and that being a southpaw is “linked to a number of factors that might be associated with reduced survivability” — sleep problems, possible neurological damage, some forms of diabetes, epilepsy, alcoholism, and “certain psychopathological conditions, such as schizophrenia.” Despite the stellar athletes, studies show that lefties tend to be clumsy. (I admit, guilty as charged.) And southpaws have a tendency to complete 90% of a job and then abandon it — for example, doing the dishes, but leaving two glasses in the sink, unwashed, for no good reason. (Again, guilty.) OK, dirty dishes, high anxiety and Jack the Ripper: Clearly, leftism is not necessarily a good thing. Still, they’re offset by Thomas Edison, half the Beatles and Bart Simpson (did we mention that Bart is a lefty?). So being on that lefty list feels so … right.