DETROIT — They range in ages and income levels. Some are divorced, others never married. Their interests vary from mushrooms to muscle cars.

But they are all adult children living at home with their parents.

Since 1970, the percentage of people ages 18 to 34 who live at home with their parents increased 48 percent nationwide, from 12.5 million to 18.6 million, according to the U.S. Census Bureau.

The practice is the focus of the movie "Failure to Launch," starring Matthew McConaughey as a 35-year-old living with his parents. And the tale of children who return to the parental nest or never left in the first place is playing out in basements and spare rooms and carriage houses all over the nation.

"I'm thinking this may be a trend," said Neal Hartshorne, 42, who lives with his parents in the Northville home where he was raised and who works in a stained-glass shop as a craftsman. "I don't make much money, so it's not sensible for me to move out."

Hartshorne is what real estate representatives often call a boomerang kid — those who tried life on their own but came back to the nest. He wasn't gone long. Right after high school, he moved to Chicago to attend a trade school. He was back home after one semester.

And by default he has the largest bedroom in the three-bedroom house — the one the three children shared as kids. As his brothers moved on and out, Neal inherited the room.

Father Harry Hartshorne, 80, said he doesn't think Neal's motivated enough to find the additional employment necessary to live on his own. Harry isn't complaining. His son's presence allows him and his wife to travel without worrying about the house. Neal keeps the grass cut, shovels the snow, does his own laundry and cooks for himself.

For tax purposes, Harry says his son pays rent $50 a month. Neal balks at such a notion. "They don't ask me for anything," he said.

"Him living here is not a problem for us," added Harry, who retired in 1981 from Ford Motor Co. "It may be a problem for him, but he's not anxious to solve it. He couldn't survive if he wasn't living here."

RETRO RESIDENCY

Experts say certain ethnic groups and cultures — Asians, blacks and Hispanics and people from Mexico and Italy — tend to have particularly close family ties and adult children who stay home longer and are less likely to move far away.

"People today do think it's a little odd when a young adult stays in his or her parents' house until their early 30s, but it wasn't that uncommon 100 years ago," says Andrew Cherlin, a sociology professor at Johns Hopkins University in Baltimore. "We're moving back in the direction where it's acceptable to stay home."

The norm of later marriage and adult children taking over the family business took an about-face beginning in the 1950s. People started marrying and moving out at "extraordinarily young ages." Now they seem to be reverting to the earlier pattern, Cherlin said.

A marriage ending and a small child to raise prompted Peter McLeod to move back into his parents' Novi house 12 years ago. Now his son, Brandon, is nearly an adult at age 17. McLeod's father, Bruce McLeod, 74, is trying to make his grandson happy by renovating the basement into a bedroom and hang room for Brandon and his friends.

Lieselotte McLeod, 75, sacrificed her sewing and painting room as a bedroom for Brandon. Bruce said he and his wife don't travel or do as much as they would if Peter and Brandon weren't still in the nest.

Though Peter McLeod has worked at IBM through a temp agency for about five years, he does not pay rent to his parents.

"I figured they'd move in for a couple years until they got on their feet — well, that's never happened," Bruce McLeod said. "Right now, I think it would be better if they weren't here, but we're not going to kick them out."