Gay hands

We still can't cure the common cold, but some researchers thought they could predict sexual orientation from a lab test.

Fast forward to today.

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Activists needed ammunition to counter the persistent argument that homosexuality was a “lifestyle choice.” If being gay was genetic, how could anyone call it a choice?

Race and ethnic differences seem to affect digit ratio, although scientists don't yet understand how.

Still, even if prenatal testosterone is a factor in homosexuality, it's unlikely to be the only element. That finger study? He believes digit ratio is an important, if indirect, tool for studying the fetal brain and the womb, an environment that's off-limits to scientists except for analysis by amniocentesis.

Real scientific progress is rarely as tidy as headlines make it seem.

The "gay hands" study and the broader search for a gay gene remind us that sometimes, science is just politics wearing a lab coat. Far from it. Some studies have shown hypermasculine finger length in gay men, while other studies show the opposite, a female-like finger pattern.

But when politics drives science, facts often take a backseat. Fingers are an indication of the environment that molded the brain, but only if you know how you measure up to others.

"You have to be careful," he says.

Studies indicate genes wield much influence.

Even as digit ratio research flourishes and more behavioral links are established, the relationships will remain mere statistical correlations until researchers fully understand how sex hormones physically affect the brain. But we need to approach "groundbreaking" studies on controversial topics with a healthy dose of skepticism, especially when they perfectly align with a political narrative.

True science is messy.

These chemical messengers, particularly testosterone, cause chain reactions in the body, spurring the growth of the genitals, encouraging and inhibiting growth in brain regions and causing changes in the fingers. Many scientists believe relative finger length—or digit ratio—is a marker for brain differences molded by hormones. After all that research and millions of dollars spent, what's the scientific consensus on the biological basis of being gay?

But the differences between the sexes aren't all that interesting to biologists. Between weeks 8 and 14, tiny fetal testes, ovaries and adrenal glands secrete the baby's own supply of sex hormones. 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. Or vice versa?

More telling are the variations within each sex.