The reason so many people love Thanksgiving is the same reason so many people hate Thanksgiving: It is the quintessential family holiday. No gifts, no religion, no parties or complicated rituals. Just a meal with relatives.

At the very least, it's predictable. Every family has assigned roles that become the stuff of family lore--Mom cooks, Dad watches football, older brother tortures younger sister. The stories, the traditions, the pecan dressing (never oysters; it has to be pecans) are all part of a well-worn and well-loved package.

Until that year when something changes: Your only son's new girlfriend persuades him to come to her parents' for Thanksgiving. The newlyweds must choose between in-laws. Divorce, death, a cross-country move can alter everything. Suddenly there's a new or different set of traditions and expectations--which is why the first Thanksgiving away from home is so revealing. The sense of displacement can also bring life-changing realizations.

One year, a 25-year-old Washingtonian announced to her parents that she would not--for the first time in her life--return to Boston that Thanksgiving. Her beau in Oklahoma, who had been flying to the nation's capital every other weekend for four months, now wanted to take her home for Thanksgiving weekend.

Miss Thanksgiving dinner at home? "The guilt was incredible," remembers the woman, who declined to be identified out of deference to the boyfriend's family. Her parents concluded that something serious was afoot; so did the woman, who could tell a marriage proposal was just around the corner.

So she flew to Oklahoma City, and was swept into the family's cherished Thanksgiving weekend tradition: attending the Oklahoma-Nebraska football game. "Didya bring something red to wear?" inquired one of the cousins sweetly. "You can borrow something if you need to." They even offered to drive to Dallas to find a suitable outfit for the big day.

This was no mere football game; it was the family's raison d'etre for the holiday weekend. Thanksgiving dinner itself was held at a local restaurant because they were saving their energy for the big game on Saturday.

"To me, Thanksgiving meant food and family," she says. "To him, it was football. It was all they talked about all weekend."

In the end, she realized to her horror that she could never marry this man or his family. She broke up with him within a week. "It would have never worked," she says.

The first Thanksgiving away from home forces people to confront their place in the world. On Thanksgiving two years ago, Raul Fernandez, president of Proxicom, a Reston Internet technology firm, was stuck in Munich on a business trip. The high-tech world is filled with unsentimental workaholics, and Fernandez had worked on other holidays, but somehow this was different.

Being in a foreign country added to his sense of isolation--"I felt like I was missing in action." He came away with a sharper sense of the line between work and family.

Christmas is full of sentiment and sharing, but it's celebrated in a number of ways: parties and open houses with friends, winter vacations, church services, collecting toys for tots, plays and concerts. Thanksgiving is a one-day gathering of family, a holiday that raises more questions of self-definition: whom we share our lives with, whom we belong to. Robert Frost never said it quite this way, but home is where they have to let you come for turkey and dressing.

That's why so many people open their homes to stray friends on Thanksgiving. The notion of spending the holiday alone seems somehow wrong, and it is always an act of generosity to extend an invitation for the day. It's much harder to be the odd man out, straddling that fine line between being a guest and being an adopted family member for the day.

"We always have outsiders, usually people who can't make it home," says Norma Ramsey, a Great Falls wife, mother and charity fund-raiser. "The most important thing is to seat them next to someone fun so they feel at ease."

Ramsey, however, has never missed a family gathering. "I count myself very fortunate," she says. "I've never had a Thanksgiving without my entire family--parents, sibling, in-laws. The holidays for us are about being together. If we go to my mother's, everybody goes to my mother's."

The desire to belong is so great that many people go to extraordinary lengths not to miss a single family Thanksgiving. Gretchen Gorog, a self-described "mother bear" of six and grandmother of 21, has produced Thanksgiving dinner for almost 50 years.

"For a family like ours, it's a major thing," says Gorog. "When the children go off to school, coming home for Thanksgiving was very important." To make her children feel loved and embraced when they returned, she started decorating her McLean home for Thanksgiving with fruit garlands and a kitchen tree with turkeys.

This year is going to be different, though. "For the first time in all those years, my daughter-in-law is having Thanksgiving," she says. "I think they really wanted to do it."

But Gorog isn't quite ready to retire her apron yet. On the Saturday after Thanksgiving, the family is coming to her house for "Moroccan Night." Gorog just returned from a trip to Morocco and has asked her children to come--in full costume and headdresses--for the evening.

How do you say "Thanksgiving" in Arabic?