When your 88-year-old grandfather sends a request to be your "friend" on Facebook, you have two choices: Either confirm it, then quickly take down all those party pictures you thought were so funny, or plan on never coming home for the holidays.

As someone who lists Pinot Grigio as a hobby, writer Beth DeFalco was seriously concerned about her grandfather joining Facebook.

She was worried her grandfather would get the wrong idea about her. Or worse yet, he'd find out exactly who DeFalco was — not the teetotalling granddaughter she'd try to portray twice a year when she went home.

And that's just what happened: "We got to know each other through a social networking site that many 30-somethings haven't learned to use, let alone octogenarians," she wrote.

"I don't browse Facebook much, but I see that it is a way to get to the nitty-gritty of a person's character," her grandfather explained. "Also a way to do something late at night when I can't sleep."

Turns out, he isn't the only one in his age group using social networking sites.

Behaviour changes if grandma's watching

Facebook estimates that it has a few million users over the age of 65. MySpace claims to have 6.7 million users age 65 and over on its site. In fact, according to MySpace spokeswoman Jessica Bass, older users are among the site's fastest-growing demographic.

Seventy-one-year-old Lynne Bundesen of Santa Fe, N.M., is one of them. Why did she join? "To keep track of what my grandchildren are doing, of course," she said.

Her grandson, 27-year-old Russell Simon, knows that but doesn't mind.

"It keeps her young to be on there, in more ways than one," he said. "She puts these very young pictures of herself up there. She was beautiful. Just seeing her when she was young, out on a boat with her hair flowing, it makes me think of her differently."

"But mostly, it's so she can spy on us, not so we can learn about her," he said half-jokingly.

Simon actually has three grandparents on Facebook. And he admits that having them there has changed his online behaviour.

"When you do status updates — sometime I forget that they're on — I have to look at it a different way," he said.

Not everyone is thrilled with the baby boomers' discovery of such sites. Some young people have responded by searching out new ways to stay a step ahead of grandma, moving from Facebook to Twitter, for example.

"I think that these developments might be the death of Facebook," said Simon's friend, Charlie Pabst.

Most users younger

Social networking sites are still predominantly used by a younger population. The median ages of MySpace and Facebook users were 26 and 27 years old, respectively. At the career-focused LinkedIn, it was 40, according to a recent report by the Pew Internet & American Life Project.

But there may be no escaping the onslaught from older relatives. Bundesen also uses Twitter to update her status. "I'm adapting to their lifestyle," she explained.

Like some younger users, Defalco's grandfather initially joined looking to connect to old classmates — in his case, any that were still alive.

He wasn't so successful there. But soon, he found that he could use it to stay in touch with grandchildren near and far.

Defalco spent a fair amount of time around her grandfather growing up in Colorado. But she never really knew him — his personality, his war stories, the story of how he and her grandmother met.

After her grandmother passed away last year, her grandfather found himself alone for the first time in 65 years. He was looking for ways to occupy his time.

So this summer, about six months after becoming a widower, 88-year-old Howard Hilt of Pueblo, Colo., joined Facebook and got to know his granddaughter in New Jersey. For better or worse.

When Defalco posted a status update about running her first mile since recovering from ankle surgery, he wrote on her page: "That's the way to go Tiger!"

He also comments on pictures.

"I sure look my age in this one, and not too good in the others either," he said of one recent picture Defalco's cousin posted. "Candid shots are too stark for me, I think."

When she sent him a list of 25 random things about herself, he returned the favour with a list of "Notes about me, Grandpa Hilt."

They were very different lists, to be sure.

He learned that Defalco once met Magic Johnson and that she doesn't prepare food using fire.

She learned that he used to make spare money as a kid by watering graveyard grass in Brooklyn; he flew B-24 bombers in the Second World War; and he worked for Anastasio Somoza Garcia, dictator of Nicaragua, as a controller in his steamship agency's New York office.

"While in Managua on a business trip (my wife accompanied me), we became embroiled in an insurrection by communists and had a ducky time of it," he wrote.

But his No. 2 random thing was Defalco's favourite. It read: "Met my future wife in kindergarten."

Before that, she had no idea how or when her grandparents met.

And despite her initial concerns, he assures her that he hasn't been shocked by what he's seen.

The reason is simple: "At my age, nothing shocks me!"