Poor parenting means children are less prepared to start school than ever, the chief inspector of schools in England has said.
Children need good verbal skills later on
David Bell, the head of schools watchdog Ofsted, said the behavioural and verbal skills of children starting school were at an all-time low, with many unable to settle and not ready to learn.
Some five-year-olds could not even speak properly when they started school, he said.
Headteachers also reported children being unable to do up buttons or use a knife and fork.
"Everyone wants children to start well at the age of five, but we know that some children are ill-prepared for starting school," Mr Bell told BBC News.
"That can mean that they don't sit still, they can't follow instructions, they don't behave properly.
"So there's a gap already at the age of five. And if we don't do something about that gap, it's going to cause greater problems as children go on through their school career."
Mr Bell said children with "difficult, disrupted lives" were having the worst problems.
"That manifests itself through their behaviour at school," he said.
"It's a complex issue but actually I believe it's having an impact on the way children are learning at school."
Mr Bell earlier told the Sunday Telegraph a lack of discipline and stimulation from parents were diluting the positive impact of rising standards in the classroom.
But Dorit Braun of parent support charity Parentline Plus said Mr Bell's comments were "unhelpful".
"Education is clearly a partnership between parents, schools and of course children," she told BBC News 24
"And if we start blaming parents for doing a bad job, it's very difficult for them to know how to work in partnership with schools."
Ms Braun said the demands on parents were ever-increasing, with even single parents being encouraged by the government to go out to work.
"That leaves them perhaps struggling less financially, but struggling in terms of work-life balance, and just having time to do all the things they want to do...
"If you're working very hard and you're tired, and your child is tired and fractious, it's not surprising that you might stick them in front of the TV while you prepare supper, or prepare lunch."
She called on schools to do more to steer parents in the right direction, and "communicate clearly with parents about what would be helpful".
"We need to be thinking more about how to relieve some of the stresses on parents, so they can feel a bit more in control of their time, and therefore enjoy the time they spend with their children," she said.