Ginger hair is often singled out, but whilst the visual difference is quite striking, when you look at the genetic code it's all but indistinguishable. The gene that can give rise to ginger hair is called melanochortin1 receptor (MC1R) and is found on chromosome 16. <br /><br />As the Ri's red-headed CHRISTMAS LECTURES researcher Andrew Beale explains, this gene controls the kind of pigment that will be produced in a person's hair. The difference between brown hair and ginger hair is down to a single base change in this gene -- an example of a "single-nucleotide polymorphism" which, unusually, causes a visible difference in that individual. For an appearance trait that has long been picked upon, it turns out that ginger hair is really quite an insignificant difference amongst the 3 billion base pairs that make up our genome.<br /><br />EXPLORE THE RI ADVENT CALENDAR: http://rigb.org.uk/advent <br /><br />With thanks to BBSRC: http://bbsrc.ac.uk/<br /><br />Don't miss the 2013 CHRISTMAS LECTURES on BBC Four, BBC iPlayer and the Ri Channel: http://rigb.org/christmas-lectures<br /><br />The Ri is on Twitter: http://twitter.com/ri_science<br />and Facebook: http://www.facebook.com/royalinstitution<br />Subscribe for the latest science videos: http://richannel.org/newsletter