Scientifically speaking, a beautiful face is the most average and symmetrical. That doesn’t mean they’re photogenic though. Oddly enough, most models have unusually strong features, and this allows the light to look more interesting and gives a more three dimensional illusion on a flat photograph. The exaggerated features also help to sell a story behind it. Also androgynous features can help. Women with masculine cheekbones or men with feminine mouths can be really striking on film. They’re not always what we would consider classically beautiful. I’ve known a few high end professional models in my life, and they’re not as pretty in person. There’s also character to consider. Sometimes someone can have a hideous feature that would make them far less attractive by traditional standards, but their uniqueness makes them a much better subject. Also, a pose or facial expression can go a long way to making an ordinary looking person more photogenic. In the end, a good photographer can find what makes a person interesting to look at, and figure out a way to capture it. In the right hands, just about anyone can be photogenic.