Your child has probably lied over spilled milk, and you didnt even know it.

A new study from the Journal of Experimental Child Psychology has found that parents are really bad at detecting a childs lies. In fact, parents dont even realize when their kid, or someone elses child, is lying to them.

Honesty is a crucial aspect of a trusting parentchild relationship. Given that close relationships often impair our ability to detect lies and are related to a truth bias, parents may have difficulty with detecting their own childrens lies, according to the study.

Researchers had 72 parents and children, who were between the ages of 8 and 16, watch a series of videos of children from the same age group. In these videos, the children were asked if they looked at answers to a test beforehand. Every child in the video denied looking at the answers, even though some had. Those in the study were then asked to fill out a questionnaire that asked on a scale of 1 to 100 how confident they were in their belief that the child was or wasn't lying.

The researchers also asked a group of 80 parents to watch their child in the same situation.

As it turned out, it didnt really matter if the person watching the video had a kid, or if the kid they were watching belonged to them or someone else, according to New York magazines Science of Us blog. The two groups of parents and the control group all had average confidence levels between 70 and 76 percent and all three groups were equally bad at knowing whether they were watching a lie.

In fact, the participants only realized kids were lying about 50 percent of the time. Most participants believed the children in the videos were being honest with everything they said, even though there were an equal amount of lies and honest statements throughout.

The researchers found parents especially wanted to believe their child was telling the truth.

In close relationships partners view each other in a more rigid way and distort inconsistent information to support their view, the researchers wrote. Individuals within a close relationship tend to hold a positive view of each other, resulting in a bias toward perceiving each other as honest. This presumption of honesty reduces ones suspicion and motivation for accurately detecting lies.

Detecting lies may be hard for parents because children who engage in dishonest activity are usually smart thinkers. A study out of the University of Sheffield found liars performed better on trivia tests than honest children. This is because lying requires thoughts and an increased memory so that youngsters dont get caught up in the lie, according to The Telegraph.

For this study, researchers had a group of children look at answers to a trivia game. The youngsters who looked at the answers and denied that they did would go on to earn higher scores in a separate trivia game.

"While parents are usually not too proud when their kids lie, they can at least be pleased to discover that when their children are lying well, it means their children are becoming better at thinking and have good memory skills," Dr. Elena Hoicka, from the University of Sheffield's department of psychology, told The Telegraph.

And though some parents may want to punish their child for lying, punishment may not be the best way to teach a child not to lie in the future. According to a study out of McGill University, telling children not to lie only makes them want to lie more.

Instead, parents will want to understand there are a variety of lies children tell for a number of reasons. Dr. Robyn Silverman, a child development specialist, told ABC News there are socially acceptable lies like enjoying what you got for Christmas, even if you didnt and then there are harsher lies.

Understanding these lies can help parents teach their children about the downside of lying.

Some do it to get out of trouble, others do it because other people might feel bad and they feel bad, and still others might do it just because they think its fun to pull the wool over somebodys eyes, Silverman said. Theres different lies. Some are socially acceptable and we say, 'Thank goodness youre lying about that sweater that grandma got you, and others, we wish they would tell the truth.

Silverman also offered some tips to ABC News about how parents can handle lying from their children, some of which weve outlined below along with other expert opinions.

Promote honesty as a family value

Silverman told ABC News that families should always promote honesty as a positive family value, since thatll make the youngster less likely to engage in the habit of lying.

Encourage truthfulness

This is an especially important tactic for parents with young children. According to Parents magazine, parents should encourage truthfulness when they can by offering mild and diplomatic responses when they catch their youngster in a lie. A harsh response or strict discipline may only encourage the child to lie more.

Become a role model

Parents can set a good example for their child by not lying, too, according to Silverman.

Next, we want our adults in our lives to show that they are a great example of truth-telling, Silverman said.

Find other avenues for them to express falsehoods and fiction

Your childs lying habits may be built on their desire to create fictional worlds. Thats why Silverman says parents should have children embrace storytelling.

We can do storytelling," Silverman said. "Lets give them a context to do that. Make up stories and let your imagination go wild.

Offer consequences

Slates Melinda Wenner Moyer wrote back in 2014 that parents can offer consequences to their children for their lies.

All this said, dont be afraid to discuss and even employ natural consequences to deter your kids from lying, she wrote. Tell little Susie that if she keeps lying, you may not always be inclined to believe what she says.