In summertime, kids have far less on their calendars than usual — giving them more time to fight with each other. Siblings in particular often try their parents’ patience and have moms and dad wondering, “OK, when does school start again?”

Meg Meeker, pediatrician, author of the book, “Hero: Being the Strong Father Your Children Need,” and contributor to LifeZette appeared on “The Laura Ingraham Show” on Wednesday to discuss the topic — and began by answering host Laura Ingraham’s questions about why her own daughter might be fighting with her brothers.

“Its called estrogen, Laura,” Meeker joked. “When girls hit adolescence — and even boys, to some degree — they are hormonally very different, and they are more impulsive and more emotionally volatile. We have to understand that.”

Meeker explained she herself had just spent a week with some of her grandchildren. “I was having difficulty because the three-year-old was biting the five-year-old,” she said.

Squabbling siblings are to be expected — it’s normal and healthy, said Meeker. “However, we really need to teach our kids that when there is arguing and rivalry, there have to be rules.”

Meeker said that when she was raising her own kids, she had “rules” for arguing. “It’s fine to be angry, it’s fine to argue, but here’s the deal: You can’t break my stuff,” she said. “I own the walls and the bannister and the stairs. You can’t kick holes in the walls, you can’t ruin my stuff, and you can’t say certain things.”

Parents have to teach kids how to argue in a healthy way, Meeker emphasized, and not allow them to be verbally abusive. “You can’t go into a job and [act that way] to your boss,” she pointed out, “or you’re fired.”

Meeker also said it’s important for parents to model conflict resolution techniques.

“That means when we yell at our kids, or we say something stupid, or we miss the mark, we have to go to them and say, ‘You know, this is what I did. I’m really sorry I hurt your feelings. I had no reason to yell. Will you forgive me?’”

Many parents grapple with the frustrating issue of what to do when kids say,”I hate you!”

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Meeker said the attitude in the home should be, “We don’t allow verbal assault.”

“So what you say is,’There are a couple of words you can’t say,'” she noted. “My husband and I were really big into teaching our kids to talk well and not use certain words. They couldn’t swear, they couldn’t say ‘shut up,’ and they couldn’t tell anybody — particularly us — that they hated us. You can feel angry, but you’re going to be reprimanded if you use this handful of words in our house.”

Drastic actions call for swift and certain punishment, said Meeker.

When her own daughter got mad at her at age 13 and told her to “shut up,” that daughter was grounded for a month and couldn’t play sports, either, said Meeker. “She had to go tell her coach why she couldn’t play in any games or practices. Let me tell you, she never told me to shut up again.”

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The effort is worth the undertaking — for children’s own good.

“We really have to take our kids’ behavior seriously, and show them that they are trainable, that we mean business, and that this is what life is all about.”

Ingraham asked Meeker what she should do if her son was mean to his sister.

“Arguing is normal, sibling rivalry is normal; wailing on each other, pummeling each other, kicking in walls — that is not normal.”

“There’s nothing wrong with [having him] do something for her [as a punishment],” Meeker advised. “He needs to make her bed for the next three days. He has to do something to make up for the offense that he committed. And that works pretty well.”

She added, “It’s really important to get kids to make up to the other kid what they did wrong. [Parents can say], ‘I want you to go back to your sister and tell her three things that you like about her, and that you admire about her, and I want to hear you say them.'”

This teaches kids that they need to close the issue and move forward.

Related: Moms, It’s Time for a Little Kindness to Ourselves

“If they never close the issue, then they’re always angry and it builds up over time,” said Meeker. “It’s also important to figure out why kids might be arguing. Arguing is normal, sibling rivalry is normal; wailing on each other, pummeling each other, kicking in walls — that is not normal.”

Meeker said that when kids do get aggressive, it may suggest that “they’re angry, that something’s going on. Maybe they’re not getting enough attention at home, or maybe something’s going on at school — so you need to get to the root of, ‘Why are you so over the top here, child?’”

And when parents have reached their limit with kids who are arguing — then what?

“Get your kids out of the room. You need to separate from them, because you’re going to lose it!” she advised. “And there’s nothing wrong with that.”

Meeker shared some other important parenting psychology as well.

Related: Kids Need to Learn Kindness, So Be Their Best Model Ever

“We end up yelling at our kids because subconsciously we feel, ‘If I were a better parent, my kids wouldn’t do this,’ and that’s not true,” she said. “Kids aren’t angels, yet we feel that if we just do the right thing, they will stay angels.”

Instead, she suggested an attitude of, “If you’re acting this way, it has nothing to do with me. My job is to try and blunt those behaviors.”

Finally, she offered hope for exasperated moms and dads. “If [you don’t see changes] happening this month or next month, hang in there. They will get the message — and they will get through this phase.”

Deirdre Reilly is a senior editor for LifeZette. Follow her on Twitter.