Brad Pitt had a "stricter approach" to parenting than Angelina Jolie, sources tell PEOPLE
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Three days after Angelina Joliefiled for divorce from Brad Pitt, PEOPLE confirmed Thursday that Pitt is under investigation by the L.A. County Department of Children and Family Services for allegedly getting “verbally abusive” and “physical” with one of their children while flying on the couple’s private plane.

Pitt is cooperating with the investigation and maintains “he did not commit any abuse of his children,” a source close to him told PEOPLE.

Meanwhile, other sources say differences over their parenting styles were a factor in the split.

Pitt, a source close to the family tells PEOPLE, has “always been stricter” when it comes to parenting the couple’s six children.

“They always had disagreements when it came to disciplining the kids,” the source explains, adding of Pitt, “He has wanted the kids to have more structure. Brad will get frustrated sometimes and yell at the kids.”

“I have never seen any physical abuse” by Pitt or Jolie, the source adds.

Jolie, on the other hand, maintains a “more relaxed attitude” when it comes to dealing with the children. During “chaotic” moments, the source says, Pitt advocated for rules, while “Angelina would plea, or not make the kids follow though.”

For more on Jolie and Pitt’s divorce, watch People Cover Story: Brad & Angelina on the new People/Entertainment Weekly Network (PEN). Go to or download the free app on your Smart TV, mobile and Web devices.

Adds a source from Pitt’s circle, “Brad is an incredibly loving father, and like most parents he understands that discipline and accountability are an important part of parenting.”

“The kids get out of control and the house was a constant chaos,” the family source says. Still, the “differences and arguments” the couple had about their children “seemed very normal.”

“They would disagree,” the source says. “It never seemed it would be the cause for a divorce though.”

FLASHBACK: Brad and Angelina at the 2012 Golden Globes

Jolie, 41, asked for sole physical custody of the couple’s kids – Maddox, 15, Pax, 12, Zahara, 11, Shiloh, 10, and twins Knox and Vivienne, 8 – in her Los Angeles court filing. Pitt sources have said he wants to share custody.