More than two-thirds of parents feel their kids' childhood ends before they become teenagers and 16 per cent said it was by the age of 10, with many blaming the Internet and celebrities.
The survey found that children are so worried about sex, popularity and their looks they are losing their innocence by the age of 12, 'The Mirror' reported.
The research, for parenting website Netmums, also found a quarter of parents feel their children become interested in sex before they are mature enough to cope.
Nearly half of parents with daughters of that age say they are body conscious and feel under "immense pressure" to be thin.
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And half of parents say their son is under pressure to believe appearance is the most important thing about someone.
"It's shocking childhood now ends by 12 years old," Netmums co-founder Siobhan Freegard said.
"The pace of modern life is snatching away precious years of childhood � they should be playing for the sheer joy of it without worrying what they look like or whether they're popular," Freegard said.