One in four teenagers thinks it is acceptable to cheat in exams, new research suggests.
And many see no harm in shoplifting or fare dodging on public transport.
The report raises concerns that many students will start adulthood believing that unethical behaviour is acceptable.
It concludes that the findings are “clear evidence” that youngsters should be given ethics lessons as part of the curriculum.
The report, which questioned 10,000 13- to 15-year-olds between 2008 and 2010, found that a quarter believe it is fine to cheat in an exam.
Girls are less likely to cheat than boys, it says, with children from working class families more likely to condone cheating than those from professional backgrounds.
Just over one in five (22 per cent) see nothing wrong with travelling on public transport without a ticket, with older students more likely to dodge a fare than younger pupils.
And nearly one in 10 (nine per cent) said they think shoplifting is acceptable. This is a 29 per cent increase from 10 years ago, when a similar survey was conducted.
But the poll did find that many teenagers have a strong work ethic and sense of social responsibility.
Seven in 10 of those questioned said they would like to make a difference to the world, while nine in 10 said they believe a good work ethic is important in the workplace.
Around half said they would like to do a job that helps other people.
In total, 80 per cent of teenagers said they believe they can do something to help the world’s problems, compared with 75 per cent who said the same a decade ago.
The Should Ethics Be Taught? survey was commissioned by the Money & Morals schools programme to mark the launch of the moneyandmorals.org website.
Money & Morals chief executive Lorraine Spector said: “It is encouraging that employees of the future are committed to being conscientious in the workplace and contributing to wider society.
“However, the consistency of the statistics from our two surveys a decade apart demonstrate a clear need for ethics to be taught as part of the schools curriculum. Teaching Money & Morals provides vital skills for students entering the workplace.
“It is good for society, good for business and, most importantly, good for students.”
The survey questioned 10,000 13- to15-year-olds in England and Wales.