Children's author Dame Jacqueline Wilson has expressed concern that youngsters are growing up too quickly.
"I think children act like adults at an alarmingly early age," said the Tracy Beaker creator.
"It's good that we want the best for our children nowadays, but perhaps we should remember they are only children and need a little loving guidance."
Her remarks came as a poll suggested that more than half of parents believe childhood is now over by 11.
The 62-year-old author, who has been writing for more than 35 years, said: "Nearly all the children in my books want to wear make-up and dye their hair and pierce their ears.
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Growing up too quickly could have a detrimental effect
John Richard Jones, Preston
"Most of my fictional teenagers want to stay out as late as possible and drink alcohol.
"Because I write in the first person people often assume that this is my point of view - but I'm actually pretty strict and old-fashioned.
"I know girls are desperate to look cool.
"But I wish they didn't all want to wear very high heels and inappropriately tight, trendy clothes."
The survey, carried out by ICM for Dame Jacqueline's publishers, Random House, suggests:
- 71% of parents allow their children to drink alcohol at home before they turn 18
- 45% of parents let their 16-year-old children sleep the night at a boyfriend or girlfriend's house
- 53% of children aged 16 and under are permitted to stay out past 11pm
- 35% of parents have allowed their under-12s to pierce their ears
- 71% of parents admit that their children have little regard for their authority
- 55% think that childhood is over by the time their children start secondary school at 11
- 72% of parents confess to giving their children a much easier ride than they received when they were the same age
- 67% of parents are worried about the company their children keep.
ICM interviewed 1,170 parents with children aged 18 or under between February 8 and 10.
Dame Jacqueline, who is also a former Children's Laureate, has sold more than 30 million books and her latest novel, My Sister Jodie, is published this month.