Would today's Major League Baseball bar Lou Gehrig? That's the argument some are using to oppose a new announcement by the MLB:  the league is conducting genetic testing on some of its new prospects, particularly those from Latin America, which is home to several players who have recently proven to be older than they claimed when signing their contracts. However, DNA testing can tell you a lot about a person, including their likelihood for future illnesses. Thus the Lou Gehrig argument—would the Yankees have turned away the Iron Horse if they'd seen in his DNA the signs of ALS, now known as Lou Gehrig's disease?

It's a complex case, but let's start with this: can you really tell someone's age by analyzing their DNA? Time Magazine asked this question last year in the wake of the age scandal for China's Olympic gymnasts. But Harvard Medical School aging expert David Sinclair told Time that all the current age-verification methods—dental records, and the rate of fusing of bones in the wrist, elbow and skull—do no better than approximating to within a couple of years. The DNA method—looking at the length of telomeres, the structures at the end of chromosomes—hasn't been reliable yet.

Major League Baseball has circumvented that problem by using genetics not to confirm a player's age, but rather his identification. Many of the Latin prospects who claimed a false identity, and therefore a younger age, did so by using somebody else's birth certificate. The MLB's new analysis is aimed at making sure a player is who he says by comparing his genetics to his parents to be sure they match. But baseball's need to know every little detail about someone before paying them has now led the league into the ocean of ethical issues connected to genetics testing. Since the league wants to test both players and parents, there's every chance they'll uncover cases where the man a player thought was his real father turns out not to be and the test throws the family into chaos.

And then there's the Lou Gehrig question. Scientific American notes that last year the U.S. passed the Genetic Information Nondiscrimination Act, which forbids American employers from asking their potential employees for a DNA sample from themselves or from their family members. The act takes effect in November, but no one's sure how it will apply to situations like Major League Baseball's, where the organization is testing foreign employees and conducting the tests outside of the country.

For the players' sake, I hope the law does apply to their cases. Given the need of pro scouts in all sports to suck up all the information they can possibly get, it's hard to imagine baseball teams would pass up the opportunity to evaluate a player's genetics in addition to his hitting or pitching skills.