Until the discovery of MAO-A, the warrior gene was just another affectionate historical nickname for Genghis Khan. Uncover a heroic heritage with today's Groupon: for $49, you get a DNA test for the warrior gene from Family Tree DNA, a $99 value.

Though nature may be nurtured to generate virtually any personality, the only way to pinpoint one's biological essence is through gene testing. A positive test for the warrior gene does not mean you are a violent person, though it may indicate a more forceful nature, aggressive reactions to perceived threats, and a deep-seated love of horned hats. The warrior gene, also known as monoamine oxidase A, has been linked to increased risk-taking and retaliatory behavior, and though no single genetic sequence can be said to determine personality, some genealogical insight may inform your self-awareness. The test is self-administered, with a simple mouth-swab and results are emailed back.

The gene is X-chromosome linked, meaning that both men and women can be tested as carriers, though men are more likely than women to exhibit the gene's attributes. People with bacterial infections such as strep throat should not take the test, as this can corrupt the test and create a great and terrible race of human-bacteria hybrids.

Reviews

Genealogy Reviews Online, 60 Minutes, and The Genetic Genealogist all featured Family Tree DNA. National Geographic Channel's Explorer examined the warrior gene in a recent episode. Family Tree DNA has more than 5,100 Facebook fans.

• I’m glad I spent the money. I discovered information about my genetic background that was very surprising. I was able to take that information and really put my family history into a historical context that I wasn’t able to do before I took the DNA tests. – Genealogy Reviews Online