WASHINGTON — A seismic shift of stuff is underway in homes all over America.

Members of the generation that once embraced sex, drugs and rock ‘n’ roll are trying to offload their place settings for 12, family photo albums and leather sectionals.

Their offspring don’t want them.

As baby boomers, born between 1946 and 1964, start cleaning out attics and basements, many are discovering that millennials, born between 1980 and 2000, are not so interested in the lifestyle trappings or nostalgic memorabilia they were so lovingly raised with.

Thanks, Mom, but I really can’t use that 8-foot dining table or your king-size headboard.

Whether becoming empty nesters, downsizing or just finally embracing the decluttering movement, boomers are taking a good close look at the things they have spent their life collecting. Auction houses, consignment stores and thrift shops are flooded with merchandise, much of it made of brown wood. Downsizing experts and professional organizers are comforting parents whose children appear to have lost any sentimental attachment to their adorable baby shoes and family heirloom quilts.

To make matters worse, young adults don’t seem to want their own college textbooks, sports trophies or T-shirt collections, still entombed in plastic containers at their parents’ homes.

The 20- and 30-somethings don’t appear to be defined by their possessions, other than their latest-generation cellphones.

MILLENNIALS ON THE MOVE

“Millennials are living a more transient life in cities. They are trying to find stable jobs and paying off loans,” says Scott Roewer, 41, a Washington professional organizer. “They are living their life digitally through Instagram and Facebook and YouTube, and that’s how they are capturing their moments. Their whole life is on a computer; they don’t need a shoebox full of greeting cards.”

Many millennials raised in the collect-’em-all culture (think McDonald’s Happy Meal toys and Beanie Babies) now prefer to live simpler lives with less stuff in smaller downtown spaces, far from the suburban homes that they grew up in.

The desire of many millennials to stay in cities rather than moving to the suburbs is instigating a rewrite of the American dream. According to the 2014 Nielsen report “Millennials: Breaking the Myths,” 62 percent of millennials prefer to live in the type of mixed-use communities found in urban centers where they can live near shopping, restaurants and work. And 40 percent say they would want to stay there.

NO NEED FOR CLUTTER

Take Kelly and Josh Phillips, who rent a 700-square-foot apartment in Washington, D.C. The couple frequently sells things on Craigslist and calls an Uber instead of owning a car. “My parents are always trying to give us stuff,” says Kelly Phillips, 29, a real estate marketer. “It’s stuff like bunches of old photos and documents, old bowls or cocktail glasses. We hate clutter. We would rather spend money on experiences.”

Her husband agrees. “I consider myself a digital hoarder,” says Josh Phillips, 33, who is opening a Oaxacan restaurant. “If I can’t store my memories of something in a computer, I’m probably not going to keep them around.”

Stephanie Kenyon, 60, the owner of Sloans & Kenyon Auctioneers and Appraisers in Chevy Chase, Maryland, says the market is flooded with boomer rejects. “Hardly a day goes by that we don’t get calls from people who want to sell a big dining room set or bedroom suite because nobody in the family wants it. Millennials don’t want brown furniture, rocking chairs or silver-plated tea sets. Millennials don’t polish silver.” The formal furniture is often sold at bargain prices, or if it’s not in good shape, it might go straight to the dump.

“Baby boomers were collectors,” says Elizabeth Wainstein, 50, owner and president of Potomack Company Auctioneers in Alexandria, Virginia, where lots of unwanted family treasures end up being sold. “They collected German porcelains or American pottery. It was a passion, and they spent their time on the thrill of the hunt.” She says younger people aren’t really that interested in filling shelves.

Kenyon says the under-35 set has always had eBay to find exactly what they wanted and aren’t as nostalgic for former decades.

Dominique Fierro, 33, a photographer and stylist who rents a condo in Bethesda, Maryland, with her husband, Titou, 33, a personal trainer, is always fending off offers.

“My family is always trying to give me stuff,” Fierro says. Every couple of months, she cleans out her closets and gives her own things away either to charities or to cousins. “I don’t want formal entertaining stuff. I have a set of white and a set of blue plates. I don’t want my parents’ silver that you have to hand-wash.”