Part 8/10:
Hair color is primarily dictated by genetics, with certain traits inherited from parents. If both parents share the same hair color, there's a high likelihood you'll have similar hair; with different colors from each parent, the inheritance can be more unpredictable—a "coin flip," so to speak. The most common hair color worldwide is black, whereas red hair is the rarest—once thought to be close to extinction, but still present in small percentages of the population. Interestingly, blonde hair is relatively recent in human history, which partly explains the historical allure and the phrase "gentlemen prefer blondes."