Researchers Confirm Correlation Between Finger, Penis Lengths

It's not just a myth, researchers say: If a man's index and ring fingers are about the same length, there really is a higher probability that the length of his penis will correlate. It's more likely to be longer, reported LiveScience on July 4.

The finding was announced in the Asian Journal of Andrology. According to researchers, the finger length/penis length correlation reflects hormone levels that influence an individual's development in utero.

"The idea that men's finger ratio and hormone exposure are linked is not a new one," the LiveScience article noted. "Studies have found that the ratio between the second and fourth finger is related to sperm count, likelihood of heart attack, hand preference, facial masculinity and more.

"One small 2002 study published in the journal Urology found a correlation between the length of the index finger and genital size in healthy men under 40, suggesting that testosterone exposure in the womb affects the growth of both."

Such hormone levels are thought to correspond with a slightly elevated chance that a male child will be born gay. Hormone levels in utero can be affected in turn, it is thought, by how many male children a woman has previously borne.

Though no definitive evidence exists to prove any theory of homosexuality, a Canadian study from 2009 does seem to indicate that a correlation exists between how likely a person is to be gay and how many male children that person's mother had prior to his birth.

The study, published Oct. 8, 2009, honed the results of earlier studies. An Oct. 8 CanWest News Service article at Canada.com reported that there had been over a dozen earlier studies that demonstrated a link between older male siblings and gay people. The latest study more clearly showed that the so-called "fraternal birth order effect" truly is a case of gay people being gay from the womb, and not being "turned" gay by their environment, their upbringing, or other factors.

That result supports the theory that homosexuality has a biological basis, rather than a sociological or psychological basis. In other words, the study suggests that being gay is neither a mental illness nor a choice. But while the results of the many studies that have been done display a remarkable consistency, the article reported, one expert issued a caveat: The older-brother theory only seems to account for one in seven gay men.

The phenomenon was first reported on in a paper by Ray Blanchard, who published his results in 2001. But Blanchard, while acknowledging the importance of the new study, pointed out that six out of seven gay men cannot be accounted for by the theory. Blanchard also pointed out that while the effect seems to be real, the numbers are quite small: the article cited him as saying that a first son has a two percent chance of being gay, while the odds for a fifth son rise only four points, to six percent.

The importance of keeping the numbers in mind is to correct fears that younger male children will probably be gay. "It can't be used as a guideline for parents making reproductive decisions," the article quoted Blanchard as saying.

Even so, the results underscore what gay men have been saying all along: while some may believe that they choose to be attracted to other men, gays say that they not made a decision in the matter: it's simply part of who they are.

The commentary on the article that was also published on Oct. 8 expressed the point of view, offered by scientists from Michigan State University, that a biological basis for homosexuality, even if it does not explain all gays, is a powerful argument against discrimination and stigmatization.

Drawing on one projection that the older brother effect can account for up to one million gay men in the United States alone, the group wrote, "If their mothers had carried only sisters before, the demographics say, those males would be straight.

"It stretches the meaning of the word to suggest that these boys and men 'choose' to be gay," the scientists wrote, going on to ask, "Who gets to choose how many brothers their mother had before them?"

Another bit of finger-sized folklore says that men with shorter index fingers than ring fingers may be more likely to be gay than men with index of ring fingers of equal or near-equal size. Marc Breedlove promoted that theory in a paper published in the science journal Nature. The paper also speculated that prenatal hormone levels can affect a person's sexual orientation from birth, and attributed difference in finger lengths to in utero hormone levels.

"If the findings hold, wrote Skidmore College biologist Denise Brooks McQuade in an editorial accompanying the study, digit ratio could provide an at-a-glance measure for doctors to gauge how much testosterone their patients were exposed to in the womb," the LiveScience article said.

That in turn could conceivably give doctors a handy rule of thumb when assessing patients for health factors thought to be related to hormone levels while still in the womb: wrote McQuade, " 'Hotness' aside, the value of digit ratio research for the biomedical scientist or clinician may come from the predictive abilities and risk-assessment qualities of the measurement for clinical conditions."