Bacteria that's crossed the blood brain barrier can affect behaviour. In European woman, the most common bacteria in a woman's vagina's is Lactobacillus largel

Bacteria that's crossed the blood brain barrier can affect behaviour. In European woman, the most common bacteria in a woman's vagina's is Lactobacillus largely due to the milk product consumption in their die. However whilst Western medicine considers Lactobacillus to be a probiotic, other cultures who do not consume milk products in as large a quantity have different bacterial profiles in their vagina's. Japanese people claim to be able to smell gone off milk oozing from the pores of westerners. The presence of a particular strain of bacteria (whose name I dont have to hand right now) in a woman's vagina will also predict whether they have freckles or not. Biology is a fascinating subject and very much open to debate.