The J.F.K. assassination. The whereabouts of Jimmy Hoffa. Causes of major disease. What do all three have in common? Questionable theories to explain each of them. Leaving my own questionable theories out on the first two, I came across a theory on the third one -- related to a person's risk for developing diabetes.

While your eyes may be the window to your soul, your eyebrows apparently are the window to your health. That's because German scientists recently concluded that eyebrow color may tell of a person's risk of diabetes. After examining the blood glucose levels of 100 men with gray hair, they found that those of them who had dark eyebrows, 76 percent had diabetes. This was compared against the mere 18 percent of men with gray eyebrows who had diabetes.

Doctors wonder if diabetes may delay the graying in the eyebrow follicles. They suggested that if your hair is turning gray but your eyebrows are still showing their more youthful colors, you may want to have your blood sugar tested.

Anyway, it's a theory. Then again, so is the idea that a single bullet can strike someone in the back of the head and...you know what, never mind.