Many parents are still undermining schools' attempts to instil discipline in the classroom, a cross-party group of MPs heard today.
Children copy the behaviour they see at home, and this can affect discipline in schools, education experts told the Commons education select committee.
During a hearing on behaviour in schools, MPs were told that "low level" disruption, such as pupils refusing to stop talking, sit down and undermining teachers was rife.
On average, 30 minutes of teaching time per teacher, per day, was lost due to low level disruption, Dr Patrick Roach, deputy general secretary of the NASUWT union, said.
Four-fifths of teachers believed behaviour was more challenging than five years ago, he said.
David Moore, an education consultant and former senior Ofsted inspector, told the hearing: "Adults have to model behaviours that they want, because otherwise how does the child learn?
"I mean, children come from homes where they see a variety of types of parenting and they bring those models with them."
Children, particularly those at secondary school, have to adapt their behaviour every time they change lessons, and an "increasing number" are finding this difficult, he said.
Teachers establish a behaviour policy for the whole school, but should explain to pupils why something is unacceptable, otherwise they do not know why something is wrong.
He later added: "If you go into any shopping area on a Saturday and you watch parents interacting with their youngsters you can see why the youngsters behave the way that they do, because they model the behaviour of the adults."
Christine Blower, general secretary of the National Union of Teachers (NUT), said there had to be a "common understanding" between parents and teachers over acceptable behaviour.
"The classic thing is that a child hits another child in the playground and the child who has been hit goes home and the parent says: 'Well just hit him back next time'," she said.
"And of course, that will not be, for the most part, be the discipline and behaviour policy that operates in school.
"There are very basic, sometimes, misunderstandings or differences of values and the difficulty for us - for teachers, school governors, and school management - is to make the bridge so that those parents who might have values that would be at variance with what the school is trying to do come to buy into it."
The committee also heard that mixed ability classes - in which pupils of differing educational aptitudes are taught together - may be contributing to bad behaviour.
Tom Burkard, a research fellow at the Centre for Policy Studies, said that children at the lower end of the ability range, or those that may have been diagnosed with Attention Deficit Disorder have problems with "working memory" - the process of putting words into sentences, to take in information and form conclusions.
"If you don't have this ability and you are sitting in a mixed ability class, which is relying to a large extent on your own, shall we say, investigations, you are going to find the whole procedure totally and utterly meaningless," he said.
"If you are lucky, the child will sit in the back of the class and do very little, if not they are going to act up."
But Dr Mary Bousted, general secretary of the Association of Teachers and Lecturers (ATL), said that in her previous experience as head of English at a secondary school, mixed ability classes worked well compared to streamed classes where behaviour in the bottom sets was "appalling".