Redheads may get their fiery persona from Mars.

Astrologers claim there is a connection between the red planet, Mars and the fiery nature of people with red hair. Redheads are notorious for their well-known hot-tempered, high strung and sensitive natures. In astrology, if the planet Mars is in your charts, it has the affect of placing fiery, competitive and  almost explosive tendencies into your behavior. Research astrologers Judith Hill and Jacalyn Thompson made a discovery in their study of 500 redheads that makes a connection to Mars and redheads. In Mars and Redheads (1988), almost 30% of the redheads had the ascending Mars in their astrology birth charts.

Source: Edward Snow Astrology News Service “The Volatile Connection Between Redheads and Mars”

There are claims that redheads came from Mars.