Q: I have heard that you can tell whether an individual is gay or straight by the length of his or her ring finger. Is that true?

A. Some researchers think that digit ratio, as it is sometimes called, is a marker for brain differences molded by prenatal hormones. They think these measurements may tell you something about what was going on in terms of levels of hormones in your mother's uterus just weeks after your conception, a time when your fingers, and more importantly, your brain, were developing.

Several years ago, an article in Psychology Today ("Sexuality: Your Telltale Fingertips") briefly discussed the relative lengths of a person's ring finger versus index finger. The author wrote, "Like a bit of prenatal graffiti, a longer ring finger says, 'Testosterone was here.'" Because of the influx of sex hormones at this prenatal stage, men tend to have ring fingers that are slightly longer than their index fingers; in females these fingers are usually the same length or the index finger is just a bit longer. Along with external genitalia, relative finger length is the other sexually dimorphic physical trait fixed at birth (other differences showing up at puberty).

A variety of studies have linked digit ratio to a plethora of things including left-handedness, heart disease, autism, aggression, hyperactivity, ADD, etc. According to Dennis McFadden, psychology professor at the U of Texas at Austin, lesbians may be more likely than straight women to have a masculine finger ratio. That does not, however, tell you anything definitively about a specific individual. In my experience, I have met straight women with longer ring fingers, who were (incidentally) excellent athletes. Consequently, you may want to avoid rushing around trying to measure the ring and index fingers of other individuals.

• If you are interested in reading more about this, the article may still be available.
• In addition, Joe Rojas-Burke recently wrote an article in LifeExtension on how to determine digit ratio.