haha, I thought this must be a joke at first, but the article is absolutely fascinating:
Infection with a common cat parasite (with upwards of 95% of the population infected in some countries) triggers differences in personality. Men become more wary and suspecious, as well as appearing more attractive to women due to increased testosterone levels. Women become more docile and trusting and dress to impress others. The parasite also seems to correlate with reduced attention span and increased chance of getting in a car wreck.
I am somewhat skeptical of the whole thing, but thought it was a very interesting read and very funny, given how much we can try and attribute to innate personality at times.