Survey results suggest that the answer is yes and no.
Most parents know their own children quite well but overestimate the involvement of other teens in alcohol and drug abuse, according to the latest results released this week of Palo Alto's annual Reality Check Survey.
Teenagers share similar misperceptions.
Most of them lead sensible lives but vastly overestimate the risky behavior of their peers, the survey stated.
At the same time, a significant minority about 19 percent of high school students are regular alcohol users, admitting to drinking at least monthly. Between 9 and 10 percent of students say they drink weekly or daily.
The results of the annual Reality Check a comprehensive web-based survey of some 5,700 Palo Alto middle- and high-school students have been remarkably consistent over six years, said Becky Beacom, a Palo Alto Medical Foundation health-education manager who has been involved since the early days of the project.
"People are underestimating the health, the kindness, the connectedness, the good parenting in this community," Beacom said.
"Does that sound like Pollyanna? It's just the truth."
On the other hand, she cautioned, real concerns remain about the minority of Palo Alto teens who are serious abusers of alcohol and drugs.
"The gap between what's really happening and what kids think is happening is very important," she said.
"It affects abstainers, who think that they're the odd ones out.
"And for the kids who are using (drugs and alcohol) and in need of help, they often delay getting help because they're comforted with the (false) idea that they're in good company.
The annual survey was begun when then-Superintendent Mary Frances Callan and then-Police Chief Pat Dwyer grew "concerned about the number of students they were seeing with drug and alcohol problems," Beacom told a gathering of some 30 parents in the Gunn High School Library Tuesday night.
"They also were concerned that young people were starting at an earlier age, but they really had no data."
The survey is managed by the Palo Alto Drug and Alcohol Community Collaborative, representing a host of community agencies including the school district, Palo Alto Medical Foundation, the police department, the PTA and the YMCA.
People were surprised and many disbelieving in the early days of the survey, when data showed that a solid majority of teens do not use alcohol, Beacom said.
But careful data screening and consistent results over six years suggest that the survey data is accurate, she said.
Because people's behavior is strongly influenced by what they believe their peers to be doing, it's important for parents and teens to get beyond stereotypes of "typical" teenage behavior and understand the reality, she said.
"If everybody thinks that everybody else is doing it, there's no amount of education or 'just say no' that's going to be effective," she said.
In the case of marijuana use, for example, 75 percent of Paly and Gunn students say they never use it, yet most students assumed their peers were much heavier users.
Forty-four percent of students said they had never been to a party where alcohol was present and, of those who had, 23 percent said they themselves did not drink.
On the other hand, about 10 percent of high school students said they would typically take five or more drinks at such a party.
"You have to keep both sides in mind," she said.
Survey data also consistently show that middle school students vastly overestimate the level of drinking and drug use that occurs among Palo Alto's high school students.
On the whole, teenagers aren't "boozing, binge-drinking party animals" in Palo Alto, Beacom said.
"It's extreme behavior, and it is not normal."
Beacom urged parents to trust their own instincts and to network as much as possible with other parents when grappling with difficult questions.
"The stereotype of Palo Alto parents is that they're in denial," she said.
"Some of that is true, but the other part of that same truth is that parents often know when something is wrong, and they're told, 'It's normal.'
"And then they start questioning their own good judgment and knowledge."