Worried about cybertheft? That’s so 20th century. Tonight’s “NOVA” (8 p.m., PBS) explores a brave new world that’s now upon us: the era of the genetic code and the powerful and potentially dangerous information it can reveal.

Our genetic blueprints can become the starting point for aggressive preventive medicine, allowing doctors to understand a cancer’s genome and learn how to attack it. We may soon be able to pinpoint medications to particular genes and diseases, methods that will make the medical “carpet bombing” of chemotherapy seem crude by comparison. “If we’re going to switch to prevention, then your own genome sequence may be one of the most critical tools you could imagine,” says Francis Collins, director of the National Institutes of Health.

But knowledge of people’s genetic makeup and defects could lead to a kind of DNA-based discrimination. Will insurance companies and potential employers start to shun people whose DNA pinpoints expensive maladies? Will it lead to a master-race-breeding mentality, affecting how individuals choose a potential spouse? Will political candidates be compelled to reveal their genetic code the way they now must release their tax statements?

Sequencing an individual’s human genome used to be the stuff of science fiction. And until quite recently its prohibitive price tag (upward of $350,000) kept it out of reach. Now companies can do it for less than $1,000 and the price continues to fall, bringing this powerful information within reach of those who could help you, or spy upon your innermost vulnerabilities.

• “Whitechapel” (9 p.m., BBC America), the stylish British detective series where criminals always hearken back to the murderous misdeeds of history, returns for a third season.

Tonight’s other highlights

• An expired license trips up a trip down the aisle on the season finale of “Whitney” (7 p.m., NBC).

• Two hours of live performances on “American Idol” (7 p.m., Fox).

• “America’s Next Top Model: British Invasion” (8 p.m., CW) travels to Canada. Banality without borders.

• Woody’s career path could turn on the determination of a victim’s cause of death on “Psych” (9 p.m., USA).

• Faced with the company’s largest order to date, the boys focus on blowing up a beaver dam on “Duck Dynasty” (9 p.m., A&E).