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If you’re easily annoyed and lose your temper often, the answer may be in your fingers. Aggression may have biological causes rooted in the length of a person’s ring finger to the index finger, according to a 2012 study. Basically, if the latter is longer, you can be predisposed to flare-ups. All of this may be due to higher prenatal testosterone exposure. However, long index fingers are also linked to lower prostate cancer risk.