Amidst the swirls of controversy that buffet other sexuality researchers, one man focuses, quietly, on swirls. In a monograph called Excess of Counterclockwise Scalp Hair-Whorl Rotation in Homosexual Men, Dr Amar J S Klar announces a subtle discovery. "This is the first study," he writes, "that shows a highly significant association of biologically specified counterclockwise hair-whorl rotation and homosexuality in a considerable proportion of men in samples enriched in gays."

Klar heads the developmental genetics section of the gene regulation and chromosome biology laboratory at the National Cancer Institute in Frederick, Maryland. His hair-swirl study appears in a 2004 issue of the Journal of Genetics.

The phenomenon is easy to overlook. Klar explains:

"Since the hair whorl is found at the top ('crown') of the head and thereby it is difficult to observe one's own whorl and the direction of orientation is seemingly an unimportant feature, most people are oblivious to the direction of their hair-whorl rotation. It takes two mirrors to observe one's own hair-whorl." His monograph includes a photograph showing the "scalp hair whorl of an anonymous man selected from the general public", and directs the reader to hold that picture in front of a mirror in order to "appreciate the counterclockwise orientation".

How difficult is it to collect hair-whorl-direction data? Klar explains that he, for one, got lucky:

"By chance I happened to be vacationing at a beach where a preponderance of gay men was fortuitously noticed. The subjects were considered to be homosexuals because of their public display of stereotypical interpersonal relationship deemed typical of homosexual men. This assessment was reinforced by the dearth of females and children on the beach ... Conveniently, the gay men were highly concentrated in one area of the beach. Such considerations made it relatively easy to collect the data on groups of predominantly gay men with great confidence even though the subjects were not asked for their sexual preference."

A year later, Klar returned to the same beach and collected another load of data.

He reports that "altogether in a combined sample of 272 mostly gay men observed, 29.8% exhibited counterclockwise hair-whorl orientation". This, he says, is "vastly different from the value of 8.4% counterclockwise rotation found in the public at large, which included both males and females".

The study does not take account of the erstwhile hair-whorl directionality of persons who are now bald. Klar explicitly excluded them from consideration, along with anyone who was wearing a sun hat.

Klar suggests a direction for further exploration: "It should be equally interesting to compare the proportions of clockwise and counterclockwise hair-whorl orientations in lesbian women with those in females at large."

The report ends with a simple notice that deftly fends off the research-is-a-waste-of-government-money crowd: "Author's personal funds were used for the study".

(Thanks to Claudio Angelo and Hanne Poulsen for bringing this to my attention.)

• Marc Abrahams is editor of the bimonthly Annals of Improbable Research and organiser of the Ig Nobel prize