At a children's party this year, I witnessed full-on "mean girl" behavior. I can't say more because I don't want to single out any children but I can tell you how horrified I was to watch this and realize these kids were still in elementary school.
She chalks it up to two reasons: girls starting to go through puberty earlier, on average as young as 9, and girls modeling what they see on television and in movies.
"Mainstream media is portraying girls at younger ages who are mimicking the worst of obnoxious, stereotypical girl behavior ... rolling eyes, moving the hips around, being catty," said Wiseman. "So what girls are getting is that by 8 or 9, this is sort of a 'normal' way to act."
In fact, research shows that the more girls watch TV shows with socially aggressive female characters, the more likely they are to model that behavior in their own classroom.
A study, conducted by Nicole Martins,
an assistant professor of telecommunications at The Media School at Indiana University, found that 92% of 150 shows popular with children included some form of relational or social aggression. The aggressive behavior was often carried out by the physically attractive female characters.
Think Hannah Montana or Sam on iCarly.
"With girls, the more they watched, the more likely they were to perpetuate these behaviors so there's something about the nature of this type of behavior that girls feel comfortable perpetuating," said Martins.
"I've argued, and many others have argued, that it's really about socialization, that as a culture, we tend to condone physical aggression with boys, and say, 'Oh that's just the way boys are' but with girls, we tell them not to do that because that's not what girls do."
So what's the message to our girls about what they can and should do when they get angry? "Girls have essentially been taught at a young age to be sneaky about it and this is what we are seeing in the shows that we are watching," said Martins.
'Boys are easy, girls are hard'
In our own conversations, we should also be mindful about how we're feeding into the stereotypes about girls and boys, said Wiseman, whose latest book "Masterminds and Wingmen"
focuses on how boys have to deal with "mean boys" too.
"We say boys are easy and girls are hard, girls are back-stabbing, nasty, all that kind of stuff, and what that means is we're basically saying, 'Well, your legacy, girls, is to grow up and be back-stabbing and not have women or girls that you can trust as friends.' "
Instead, Wiseman said we should be telling our girls that they deserve to go through adolescence and adulthood with very strong female relationships, understanding that they will get into conflicts and that people will be mean to them at times, but being able to advocate for themselves when that happens.
"Here's what I say to parents: You cannot prevent conflict. You cannot prevent all mean girl problems that your daughter is going to have. You cannot. What you can do is teach your child that conflict is inevitable and they need to learn how to manage that."
What we also need to teach our girls, said Michelle Anthony, co-author of "Little Girls Can Be Mean,"
is that a "certain kind and amount of meanness" is OK. What she means by that is we want our girls to have a sense of "agency and power" especially going into the teenage years.
"So trying out meanness is not something we can or should eradicate," said Anthony. "It's normal to want to feel powerful and to exert influence on your environment. It's healthy. What is unhealthy is when the means by which a child does that is at the social expense of another."
The takeaway for parents, she said, is helping girls understand the normal and healthy part of power-seeking while at the same time helping them realize the best means to achieve their goals without hurting others in the process.
And yes, parents, our kids learn by example. "The more meanness they see being successful or rewarded in the home or in their environment, the more children will revert to those mean behaviors themselves when faced with challenging social situations," said Anthony.
So if we are snarky about another woman in person, behind her back or on Facebook, our girls are getting the message that that's an OK way to treat other girls.
"We talk about role modeling but very rarely do adults look at their own behavior and say 'What am I doing?' " said Wiseman.
Wiseman also said it's not just what we say and do, but what we watch that sends a message to our daughters.
She brings up the popularity of the "Real Housewives" reality show series and how some women call watching the shows their "guilty pleasure."
Your daughter "walks in the house and sees that's what you entertain yourself with is watching other women be mean to each other or be ridiculed or dismissed," said Wiseman. "You are showing that that's entertaining to you and then it normalizes it."
"So those kinds of guilty pleasures have way bigger consequences than you just sitting down and watching that show."
Do you get think mean girls are getting younger? Tell Kelly Wallace on Twitter
or CNN Living on Facebook