Personalized medicine current being developed prefigures a day when everyone’s genome will be deposited on a chip or stored on a gene card tucked into a wallet.

Physicians will forecast illnesses and prescribe preventive drugs custom-fitted to a patient’s DNA, rather than the one-size-fits-all pharmaceuticals that people take today. Gene cards might also be used to find that best-suited career, or a DNA-compatible mate, or, more darkly, to deny someone jobs, dates, and meds because their nucleotides don’t measure up.