The parent of any toddler can tell you: Kids lie. What’s less clear is why toddlers lie. Sometimes, it seems almost pathological. Asking a child with chocolate icing all over her face if she ate the last piece of cake – only to hear a, “No!” – can leave parents dumbfounded, or worried their child was born with a skewed moral compass.

So we looked into it and discovered three things every parent needs to know: First, that all kids lie. Second, that lying at a young age is a sign of intelligence. And third, we – parents – enable it even when we think we’re not.

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It’s not just your kid.

Children may begin lying as early as 2 years old. In fact, one study found 20% of 2-year-olds lie. And as they age, they lie more. The same study found 90% of 4-year-olds could lie; according to a New York Magazine article by Po Bronson, author of NurtureShock: New Thinking About Children, “a 4-year-old will lie once every two hours, while a 6-year-old will lie about once every hour and a half” in their natural environments.

In other words, an honest kid is a rare bird.

Children tend to tell four types of lies, according to Michael Lewis, a pediatrics and psychiatry professor at Rutgers University’s Robert Wood Johnson Medical School: a lie that protects someone else’s feelings (“I like your gift”), a lie that protects themselves (“I didn’t hit my sister”), a lie to themselves (“I’m not scared, I just don’t want to”), and a lie to hurt others (“He called you fat”).

But that doesn’t fully encapsulate why kids lie. The lies of very young children don’t fall so obviously into these categories. Toddlers’ lies can sometimes seem like a form of imaginative play intended to test the boundaries – of reality (“She’s my brother” or “I don’t want to use the toilet because last time there was a lion in the bathroom”) and of authority (“Dad said I could have ice cream for breakfast”).

But even this serves a purpose; pretend play is how children learn to make sense of the world. Making a silly statement – a ‘lie’ – like, “She’s my brother, not my mother,” allows someone else to verbally reinforce the actual relationship, and thus, strengthen the toddler’s understanding of it.

Lying takes smarts.

According to two academics who have delved deep into the reasons children lie, lying is an important sign of growth that shouldn’t dishearten parents completely.

“It’s a developmental milestone,” says Dr. Victoria Talwar, assistant professor at McGill University in Montreal, in Bronson’s article.

“Those who have better cognitive development lie because they can cover up their tracks,” says Dr. Kang Lee, director of the University of Toronto’s Institute of Child Study, in an article by the BBC.

It takes a lot of brain power to lie — Lewis estimates that the liars in his experiments are about 10 IQ points ahead of the truth-tellers. That’s because lying requires a child to recognize the truth, conceive of an imaginary, alternative version of events, and then pretend it is real. (It’s no coincidence lying often starts around age 2 or 3 – right as kids’ imaginations develop and they begin to engage in pretend play.)

Lying also requires an understanding of perception – that other people have different thoughts and beliefs (a concept called ‘Theory of Mind’). And it requires a level of emotional intelligence. In fact, according to Lewis, “children who are more emotionally stable, these are the ones who are likely to lie than to tell the truth.” (Though as children grow, frequent lying can become a warning sign of troubled emotions.)

We’re all doing it.

Most experts – Kang, Lewis and Talwar among them – agree the main reason why toddlers lie is that they see their parents do it. According to Bronson’s reporting, “When adults are asked to keep diaries of their own lies, they admit to about one lie per every five social interactions, which works out to one per day, on average.”

We lie about enjoying an activity (“That was a great concert”), about liking a person (“He’s a sweet kid”), gift (“I love this, thank you”) or food (“That meal was delicious”). We lie about our appearance (“I just wake up like this”), our emotions (“I’m fine”), our whereabouts (“I’m only five minutes away”). All of these are white lies that we distinguish as more acceptable than deeper deception, and while children are capable of making this distinction, too, the example is set and the foundation is laid.

In fact, mixed messages from parents is another reason why toddlers lie. Parents often explicitly encourage kids to lie (to be polite), or at least not to tell the truth (don’t tattle). As Bronson writes, “[Kids] learn that honesty only creates conflict, and dishonesty is an easy way to avoid conflict.”

Oftentimes, too, our reaction to misbehaviour sets up children to lie. When we ask the child with chocolate on her face if she ate the last piece of cake, she senses she’ll be in trouble if she says yes — so the only other option is to deny it. As kids age, the tell-tale smears get wiped away, but the instinct to lie out of self-preservation remains.

So, what is a parent to do?

If honesty is your goal, avoid punishing toddlers when they’re caught in a lie. Studies show that it will only cause your child to become better at lying more quickly in an effort to dodge discipline.

Instead, take the moment to communicate how much more you value their honesty than their lies. In one of Talwar’s studies, when children were read a story with that message before being put in a position to lie, lying reduced by 43% compared to the control group. A separate study found kids lying roughly 50% less when a researcher told children how happy they would be from hearing the truth.

Interestingly, telling kids that honesty is the “right thing” doesn’t work nearly as well, and only succeeds when paired with the promise of no punishment.