Yesterday, I wrote (jokingly) that the U.S. men's gymnastics team is un-American because a set of identical twins—Paul and Morgan Hamm—is on the roster. Readers disagreed. Along with those who accused me of twinophobia, quite a few argued that the premise of the piece was flawed. That's because an Aug. 13 Associated Pressstory says that the identical-looking Hamms, though "perfect for a Doublemint commercial," are in fact fraternal twins.

But are they really fraternal? Media organizations, the U.S. Olympic Committee, and USA Gymnastics can't get their stories straight.

In the last few months, the Chicago Tribune, Washington Post, Knight Ridder, and the Los Angeles Times, among other news outlets, have referred to Paul and Morgan as identical twins. The New York Times called them identical in 2002. Before and during the 2000 Sydney Olympics, the Hamms were identified as identical twins in the NYT, Newsweek, the Boston Globe, USA Today, the Washington Post, Sports Illustrated, CNN.com, and the Associated Press.

Those calling the Hamm brothers fraternal include People magazine, which profiled the brothers in this year's "top bachelors" issue, and the AP (in both 2000 and 2004). Since 2000, the Milwaukee Journal Sentinel, published in the Hamms' home state of Wisconsin, has consistently referred to Morgan and Paul as fraternal twins. In 2000, New York Times columnist George Vecsey said Morgan and Paul were fraternal three days after his colleague Selena Roberts said they were identical.

A representative at the U.S. Olympic Committee media center in Athens said the brothers are identical twins. Brian Eaton, a USA Gymnastics representative in Athens, insists they are fraternal, writing via e-mail that it comes "straight from the mouth of Morgan [Hamm]." But, in a 1998 interview posted on the USA Gymnastics Web site, Paul Hamm doesn't correct a questioner who asks, "Do you two play jokes on your coaches or teammates because you're identical twins?" Instead, he just responds, "No, it's actually pretty easy to tell us apart in gymnastics."

Nancy Armour, who wrote the recent AP piece that called the Hamms fraternal, also says via e-mail that she got the word the twins are fraternal from the twins themselves. Washington Post deputy sports editor Tracee Hamilton writes in another e-mail that Liz Clarke, who's covering gymnastics for the WP in Athens, says the Hamms are, "Identical. No Question."

Some publications wisely avoid the debate by just referring to the Hamms as plain old twins. (The encyclopedic, quasi-official Hamm twins Web site, for one, doesn't come out either way.) There seem to be no repercussions for just taking a guess, though. As far as I can tell, no publication has ever issued a correction for incorrectly calling Morgan and Paul identical (or fraternal) twins. That includes the New York Times and the AP, which have called the Hamms both identical and fraternal over the years.

Twin experts say the only way to know for certain whether twins of the same gender are identical or fraternal—or, to use the preferred scientific terms, monozygotic or dizygotic—is to conduct a DNA test. At this point, it's unclear whether the Hamm twins have had such a DNA test. An interview with Morgan and Paul's parents will hopefully provide some clarification. Another update to follow shortly.