So why isn't Fluffy interested in a single chocolate chip, while it's all you can do to keep Fido from eating the entire box? Well, according to this Washington Post article, it's because cats can't taste anything special about the cookie:

Until now, scientists have not known whether cats simply lack the lingual apparatus to detect sugar; or have functional sugar detectors on their tongues but faulty wiring from their taste buds to the brain; or -- as some might presume -- are simply too snooty to admit to such a common craving.

Now researchers studying the DNA of house cats, tigers and cheetahs have settled the question: Cats both large and small harbor a genetic mutation that renders the sugar detectors on their taste buds inoperative.

So much for my mom wanting to come back in her next life as a cat.