Why do children lie - and when do they start doing it?

"Yes, this is so spot on for us!" says Zoe Y, a mum in our Facebook community. "Our 4-year-old only began to tell lies when he started school and started mixing with slightly older children. We are currently trying to teach him why lying isn't the right option..."

The really fascinating thing, says Dr Sam, is that, when it comes to lying, there's a noticeable difference between 4 and 6 years olds – both in terms of 'skill' (how well they lie), how often they do, and how they feel about the lies they tell:

Four-year-olds are very bad at lying, and they don't enjoy it. But they get better at lying and, by 6, they enjoy it.

Children fibbing laughably 'badly' at 4 or 5 is certainly something that chimes with Kayleigh A in our Facebook community. "My 5-year-old decided to practise his handwriting in ballpoint pen over his bedroom wall, and then he lied and blamed his sister. If his sister, who's 3, had handwriting skills like that, I would be impressed!"

So why do children enjoy telling fibs more the older they get?

In essence, says Dr Sam, 6-year-olds (and older) are more like teenagers in wanting to impress their friends, even if that means lying, and they'll want to do everything they can to establish and maintain friendships.

Four-year-olds are also in touch with what they want and what they're thinking. Six-year-olds are more interested in what their friends think.

Lying 'together' against an adult is something slightly older kids will use to forge friendships – and we have an example of this from mum Michelle B in our Facebook community:

"My older children are 5, nearly 11 and nearly 13. I’ve never really had situations where they have told proper outright naughty lies, or lies to stir trouble. It’s more the sort of things like, something got broken but not one will own up and if asked was it you, they would all say no.

"Or if I ask 'Did you eat all the chocolate?' again the answer from all of them will always be no – but it clearly was one of them!"

The other side to children getting better at lying as they get older, says Dr Sam, is they'll also be likely to spot if you're telling them a fib. (Be warned!)

But this will also change their concept of joking around and telling tall stories, too. "A 4-year-old can't tell if you're telling the truth or not, so they won't like this kind of joke," says Dr Sam, "but a 6 year old will really enjoy it."

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Dr Sam Wass has been helping parents encourage their children to develop skills such as creativity, problem-solving and teamwork through creative play with LEGO City