And guess what? Watching TV while eating may not be the end of civilization as we know it. In a 2009 study of 806 teenage girls, Professor Neumark-Sztainer concluded that watching television during dinner had little impact on substance abuse rates. What mattered was that the family ate together. (“Though I’m not a proponent of watching TV at dinner,” she added.)

And for those who think family dinners should include thoughtful exchanges and revelations? Tell that to a 14-year-old. Amy Middleman, an adolescent medicine specialist at Texas Children’s Hospital in Houston, said that the dinner table may be the last place a teenager chooses to drop a humdinger. “There’s too much time to see your parents’ reaction and their over-reaction,” she said. “That’s why they prefer to drop them just as they’re getting out of the car.”

Dr. Middleman herself has three children, ages 5, 9 and 11. Her schoolteacher husband usually gives them a late snack and helps prepare dinner, so that they all sit down by 8 p.m. She believes in the family dinner. She counsels patients with eating disorders to eat with their families. And yet she is not certain that the fundamental element of “family dinner” is even food itself.

“The family dinner research may be telling us that that some of the more important elements may be about slowing down, organizing our lives with a little bit less harried time,” she said. “There just needs to be some element of structure and reconnection during the day. And I don’t know that it has to be ‘meaningful.’ It could be a drive, a walk, a regular conversation.”

To separate from the family in a healthy way, Dr. Middleman said, a teenager “has to have some level of reassurance that when they come back, what they left will still be there. And so whatever it takes to make that clear is probably what we’re getting at with ‘family dinners.’ ”

Image MAKING TIME FOR ONE ANOTHER The Perham family at the Steam Room in Port Jefferson, N.Y. Credit... Maxine Hicks for The New York Times

By that measure, Mrs. Rubio, laughing with her tumult of teenagers as they gobble from paper bags in the parking lot of the Sonic, is doing a pretty good job.