Kelvin Murray via Getty Images 7 year old boy walks down path through woods

My husband and I recently received a note home from the school teacher of our eight-year-old son, Casey. She wanted to inform us that Casey had been caught lying about a misdeed, and that this wasn't the first time. Our response? We whooped and high fived.

Yes, that's right -- we gave each other a high five. Why?

Because lying is a developmental milestone that Casey hadn't yet reached. You don't realize how important deceit is in day-to-day social interaction until you have a kid who can only speak truths. Loudly. In public places.

Lying is often viewed as a negative behaviour, particularly when used to conceal a transgression, but it is also essential for getting along socially -- those pretty little white lies.

It also reveals a sophisticated cognitive ability, something the experts call "theory of mind" -- when a child grasps that others have feelings and beliefs that may be different from their own. It also demonstrates attainment of 'executive function' or the ability to self-regulate personal behaviour and action.

Recent research has shown that by age two, 30 per cent of kids can tell a convincing lie, by age three, around half can do it, and by age four, about 80 per cent can lie successfully.

Casey has autism, a neurodevelopmental disorder that is often characterized by difficulties with verbal and social communication and rigid, restrictive and repetitive behaviours, among other characteristics. His inability to deceive -- or rather, his ability to tell it like it is -- it turns out is a common trait among those with autism.

Milestones can be critical markers on the path to maturation -- but they can also be minefields.

Several research studies have shown that kids with autism experience more difficulty lying than their typically developing peers. Others studies show that when they are able to tell a lie, they have difficulty maintaining it. They also have more difficulty understanding when others are lying to them.

Many researchers believe it's because those with autism often lack 'theory of mind' and thus the ability to instill a false belief in the minds of others. Others refute this theory, but one thing is clear: lying is a challenging 'skill' for those on the spectrum.

So were we right, as the parents of a child with autism, to celebrate a lie?

Milestones can be critical markers on the path to maturation -- but they can also be minefields.

When I was pregnant with my first child, I bought half a dozen books to guide me through the life-altering event. They were full of "dos and don'ts" -- but there was one thing in the litany of advice that all the books had in common. They all measured the pregnancy, and then, the development of the child, in terms of milestones. First you reach one marker, then you move on to the next, in nice, clear, seemingly choreographed steps. The perfect pregnancy, the perfect child.

And so it went with my first child. I had the model pregnancy, and then the baby who met all the milestones one by one, in the allotted time. It was a synchronized dance with the guidebooks anticipating each step along the way.

But with my next child, Casey, everything was different. He was a wildcard.

What I didn't know then is that I should've just thrown the guidebooks away.

The pregnancy did not go smoothly and his early development as a baby was more erratic. The milestones would come, but not in the allotted order, and not in the anticipated time-frame. More advanced skills would come before more basic skills, and sometimes he'd attain skills only to lose them later and have to relearn them. Sometimes the skills didn't come at all.

It wasn't until he was four years old that he was officially diagnosed as having autism.

Then the guidebooks that were once so comforting and anticipatory, became damning indictments of everything that went wrong. Milestones stopped being gentle markers of accomplishment through time and became the noose around our necks instead. Every milestone missed was a failure, a flashing light signalling where things had gone wrong and where development had stalled.

Milestones also became the weapon many experts would use to test and assess and classify our son by his deficits.

What I didn't know then is that I should've just thrown the guidebooks away. When you have a child with autism, the child becomes the guide.

We finally chucked the experts who judged Casey solely by what he could not do and replaced them with those who focused on how he learned instead, using his strengths and interests to guide the path to development. And it worked.

Typically developing kids often learn in gentle developmental curves built from practice and steady achievement. But we found with Casey that he often has long plateaus of learning followed by rapid spikes of development that are almost uncanny to those not familiar with an autistic trajectory.

We've come to recognize Casey's atypical development for what it is: uniquely his, and already full of peaks of achievement that perpetually surprise and exceed all expectations -- with many more yet to come.

We were right to celebrate the lie because it is a new skill -- and a milestone along Casey's development. But what it is not is a useful measure of comparison to his peers -- because their map is not his, and once you understand that, you understand autism.

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