Researchers have found the key to determining high or low levels of testosterone in men without a blood test.
Testosterone is the male sex hormone that controls masculine features in men.
Testosterone is secreted by testicles in men, and to a lesser degree, the ovaries in women.
Studies have shown the length of a man's index finger is directly linked to the level of testosterone he was exposed to in the uterus before he was born.
For instance, if the index finger is shorter than the ring finger, it indicates high testosterone levels, and the opposite for low testosterone.
Researchers also noticed a strong correlation to testosterone levels and a boy's facial features.
Studies are ongoing, but researchers have determined that boys who were exposed to lower levels of testosterone in the uterus tend to have feminine features, while boys who were exposed to excess testosterone have masculine features.
For instance, boys exposed to lower testosterone levels have weak jawlines, long or pointy chins, larger foreheads and smaller, wider eyes.
Boys exposed to excess testosterone have square or strong jawlines, shorter foreheads, prominent brow ridges, larger noses, and sometimes their eyebrows are closer to their eyes.
There is also a tentative link to testosterone levels in the womb and whether a man sires boys or girls.
For instance, Golden State Warriors star Steph Curry has feminine facial characteristics, meaning he was exposed to lower levels of testosterone in the womb. Curry has 2 girls with his wife, Ayesha Curry.
Contrast that with singer Usher Raymond who sired 2 boys with his ex-wife Tameka Foster. Usher's facial features are characteristic of higher exposure to testosterone in the uterus.
Research is ongoing, and it certainly doesn't mean Curry will never sire a boy.
Study the images of the celebs below, and judge for yourself if the research is correct.