In Japan, "Ketsueki-gata” has been a belief for over 90 years. It states that a person’s ABO blood group significantly contributes to their demeanor. This is comparable to astrology, but blood type is a genetic component of humans and personality may also be influenced by genes. As the 1990 Minnesota Twin Study showed, twins that were raised apart developed similar social attitudes although they grew up in different environments, showing a correlation between genes and personality. This study tests if blood type influences personality and seeks to establish credibility of the personality-blood type phenomenon. Through an online survey, participants were asked to provide their blood type and complete a personality test that measured levels of openness to experience, conscientiousness, extroversion, agreeableness, and neuroticism. Results were converted into scaled scores, averaged, graphed, and analyzed using CHI square. Through the statistical analysis of 100 adults, their personality tests using the Big 5 Personality Traits model, and their blood type, no correlation was found. The null hypothesis of the CHI Square test failed to be rejected leading to the conclusion that blood type does not influence personality.

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