Ahead of the Bell: DNA testing companies (AP)

Police hunting a serial rapist in the French city of Marseille have used DNA evidence to arrest two men, but are unable to say which is the culprit because the pair are genetically identical. After tracking down a suspect with help from video surveillance and a victim’s traceable cellphone, investigators discovered he lived with his identical twin brother, and now face the prospect of lengthy and expensive scientific testing to distinguish between their genetic codes, if that is even possible.

Genetic scans are getting cheap enough to become a routine part of medical care. But just because they can be doesn’t mean they should be — and the economic case for genetic medicine is far from settled.  

The U.S. Supreme Court is going to hear a huge genetic privacy case this month that one top high court expert called the "most important, overlooked case of the term."

I'm standing in a balmy room kept warm because the chemicals swishing through dishwasher-size machines on either side of me like it that way. The light is low as small robotic arms inside the devices—they have clear, Plexiglas housings—are moving around samples of DNA, injecting them into flat, microfluidic chips that are a key component of separating out each of the six billion G's, T's, A's, and C's embedded in a human cell. 

TORONTO — A man who believes he’s the son of former prime minister John Diefenbaker is pleading to have his mother confirm his paternity, now that he’s drawn a disappointing blank in his latest bid for genetic certainty. Exhaustive DNA tests on a tooth found in a museum in Saskatoon were unable to come up with a definitive match to end George Dryden’s quest once and for all.