http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4158978/
Researchers in Sweden compared the digit ratios of self-identified feminist women to the female population norm. Apparently, the digit ratios of feminist women are much closer to those of the male population. For those who don't know, the digit ratio is the ratio of the index finger length to the ring finger length. For men, it's around 0.94, and it's about 0.96 for women. One of the strange effects of testosterone is that it tends to make the ring finger longer w.r.t. the index finger. Digit ratio can be used to estimate in utero testosterone exposure, and it's also a strong predictor of prostate cancer risk in men, with more "masculine" ratios having an increased risk of prostate cancer. Some speculations (though I don't know about the outcome) were made that digit ratio could be used to predict homosexuality in males.
Long story short, it seems like self-identified feminist women have (to a statistically significant degree) a highly masculine trait, one which is purely biological and can't be learned. The researchers think that it may explain the "feminist paradox" of why so few women identify as feminists despite claiming to care about women's rights. Regardless of what the study actually proves, it's still very interesting. I'd like to see a companion study on self-identified "feminist" or "feminist ally" males. This certainly doesn't prove that all feminists are lesbian man-haters who simply wish they were born male, but maybe it shows that masculine women are more driven toward feminism because they would rather have male gender roles than female.
