Can you judge a man's faithfulness by his looks? Physiognomy believers will say yes; skeptics will scoff at the idea. It's highly controversial, but some scientific findings (yes, studies have been conducted to research this!) and experts hint that there may well be a link between a man's physical traits and his predisposition to cheat.

But don't freak out just yet. Just because a guy possesses these traits doesn't mean he's definitely a cad who will stray -- people still have the ability to choose not to do these things, says celebrity psychologist and relationship expert Dr Phil McGraw.

Portrait of a cheat

His face...

Men with high testerones have highly masculine facial features -- think strong jaws, prominent cheekbones, and more-than-average hairiness. Testosterone has a potent effect on libido, and high testosterone males cheat more, divorce more, spend less time with their children, but are also highly driven.

His fingers...

Having a ring finger that's longer his index finger is an indication that a man was exposed to more testosterone before birth. And it's linked to the increased likelihood of a greater number of sex partners and a higher risk of cheating, according to Dr Phil.

His hair...

If he spends a lot of time on his long floppy hair, watch out. "Men with hair that is short at the sides and longer at the front are self-centered, self-obsessed, and least likely to worry about the effects of an affair on you," says Tracey Cox, sex expert and author of Supersex.

His testicles...

The bigger the size of his package, the more sperm he produces and the more he's ruled by his libido.