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The most recent research I can find is from 2019 that showed significant preferred on O type.
https://article.sciencepublishinggroup.com/pdf/aje.20190302.13/5027f7c4-a753-4b62-84fa-4962a2831d76/nny6
I am O+ and have heard this but also seen studies that proved it was unrelated.
Studies newer than this 2019 one?