Today's corporate culture was pioneered in Silicon Valley. Flextime, open plan offices, everyday casual dress... it all started in high tech then spread to the rest of the business world.

Well, yet another Silicon Valley cultural touchstone is now becoming commonplace everywhere else--the habitual treating of the Gen-X cohort (in general) and Gen-X women (in particular) as personnel-non-grata.

Silicon Valley job descriptions have long featured the dog-whistle of "digital native" to disqualify older candidates. Not surprisingly, as the Motley Fool recent pointed out, fully 28 of the 32 most successful U.S. tech companies have a median age of less than 35 years,

This tendency to favor youth over experience has quickly spread to other industries. As perfect example of this, here's a quote from an article entitled Why You Must Hire Younger Workers and How To Do It, published by American Express for its business clients:

"Generation Y has grown up with access to cutting-edge technology, and so has an innate ability to master it. Because of that second-nature skill, they have readily integrated technology (smartphones, Web-based tools, text messaging, etc.) into their daily lives."

The basic premise, of course, is ridiculous. No generation has an innate ability to master cutting-edge technology. In any case, it's not like today's swipe-left technology is particularly difficult to master.

Nevertheless, companies both inside and outside high tech are determined, not just to avoid hiring Gen-X, but actively seeking to drive them away.

For example, many companies have mandatory team-building exercises, like laser tag and indoor sky-diving, that are virtually guaranteed to make the average middle-aged businessperson feel ill-at-ease and out-of-place.

Similarly, everyday casual dress at work--another high tech cultural transplant--greatly favors the young. Traditional business garb, like a tailored suit, minimizes middle-age spread. By contrast, when the corporate uniform consists of jeans and T-shirt, one has little choice but to let it all hang out.

Rightly or wrongly--no, scratch that--wrongly, women at work are held to a higher standard of appearance than men, and thus are more pressured to appear youthful. Not surprisingly, an increasing number of Gen-X women are turning to plastic surgery to disguise their age.

To make matters worse, open plan offices create a corporate fishbowl that's actively hostile to older women. A recent study of 1,000 employees who moved from traditional into an open plan offices found that

"when changing from a more closed, compartmentalized office space to a new open-plan, transparent and fluid working space, office workers were more conscious of their visibility and often found this unsettling rather than liberating. Women in particular felt anxious about the idea of being constantly watched, and felt they had to dress in a certain way."

So there you have it. As Time magazine recently pointed out in an article entitled Age Discrimination Hurts Women Workers, experience is still valued in fields like medicine, law, and academia, but

"in the industries that are evolving to keep pace with the digital world, including media, advertising, publishing, communications, entertainment and even retail, age discrimination is rampant."

What can be done? Not much, at least in the U.S., since the government and courts rarely enforce age discrimination laws. Like it or not, favoring youth over experienceappears to be the management fad du jour. And, as has been sadly true in so many cases, it's Gen-X who's stuck bearing the brunt.