The documentary The Wolfpack goes inside the lives of six brothers – Bhagavan, Govinda, Narayana, Mukunda, Krisna (now Glenn) and Jagadesh (now Eddie) – who allegedly grew up locked in a New York City apartment, rarely visiting the outside world.

According to the film, their father, Oscar, was the only one who had a key and would only allow the children to leave a few times a year at most.

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Details in the documentary reveal they relied on watching movies to cope with their isolation. When they weren’t being homeschooled, they were glued to the television, taking in the work of directors like Quentin Tarantino. And when they weren’t watching, they would recreate scenes from the movies and film themselves in elaborate costumes on self-made sets. (A sister, Visnu, also lived with them but is not featured in the film.)

In May, PEOPLE interviewed four of the six brothers, all of whom now have jobs and come and go freely on their own. They also have social media accounts including Instagram and Twitter. And they are flying all over the United States to promote their Sundance Film Festival Grand Jury Prize-winning film.

So how could six brothers grow up in such an unusual environment – and turn out to be intelligent, sociable adults?

PEOPLE talked with experts to learn more about how a case like this could happen.

How can they seem so well-adjusted after the lifestyle they had growing up?

When PEOPLE met the four brothers, they were friendly, professional and polite, all standing up to shake a reporter’s hand and making eye contact when introduced. A fifth, Eddie, sat in the back corner of the room with dark sunglasses on and did not participate in the interview, but shook a reporter’s hand at the end while leaving.

Dr. Kristin Carothers of the Child Mind Institute says “normal” behavior from children who have been raised in a “non-normal” situation is in part due to humans being very resilient and having the support of each other.

“The fact that they went through this experience together, and that they had [the director, Crystal Moselle] take an interest in them and let them know that the world is safe, might contribute to the fact that they are able to come out into the world even though they’ve had this negative experience,” Carothers says.

Even though people may go through traumatic experiences, it doesn’t mean that those experiences will define the rest of their lives, says Carothers.

“It’s also possible that they’ve done some quick learning once they were able to leave the house and they were able to see, ‘Okay, this is different than what we saw in movies and maybe there are other ways to look at the world.’ ”

Was what happened to them legal?

Attorney Peter Brill, of Brill Legal Group, says someone would have needed to report the situation for it to have been investigated.

“If there’s no obvious neglect or abuse – even though I think imprisoning your children for years on end without letting them go outside is pretty neglectful and probably abusive – the question is how do people find out about it and how do authorities find out about it?” Brill says.

A spokesman for New York City’s Administration for Children’s Services would not comment about whether staffers ever visited the Angulo family and said the abuse would have needed to be reported to them (from within or outside the home) in order for them to take action.

“If there is a report, we would go to the house and interview the kids, interview the parents and evaluate the safety and concerns of the children,” the spokesman tells PEOPLE.

Children trapped in homes by the power of their parents is not something they see often in New York, he adds.

Brill says there is a crime in New York called “unlawful imprisonment” but there has to be proof the individual wants to leave and is being held against his or her will. In a case involving parents and children, it would be hard to prove.

“So if it’s not unlawful imprisonment, it wouldn’t necessarily be a crime, it’d be family court-type violations of child abuse and child neglect and those can be civil if they’re lower level or criminal, obviously, if there’s physical harm,” Brill says. “I think a family court judge would determine this is at least neglectful. Whether it was child abuse – I don’t know – but neglect is a lower standard.”

How will watching so many violent movies affect the kids?

“If you have kids that are watching violent movies or psychological thrillers, then they’re not going to see models of, what do you do when someone is your friend or you like someone,” Carothers says. “The other thing is that they may tend to overinterpret people approaching them or people attempting to embrace them, in negative ways because they don’t really know that an embrace could be a positive thing.”

During PEOPLE’s interview with the brothers, Narayana said it was really surprising to him that friends hug each other when they say hello or goodbye.

Carothers says that reaction shows that the kids didn’t have the opportunity to see positive ways to interact with people.

“If they were watching lots of dark and violent films then they might be led to believe that the world is a dark and scary place and that the way people treat each other all the time is in negative ways,” Carothers says.

How did no one know this was happening?

The children lived in public housing with their father and mother, Susanne, 60. “Her children were hers and living with her and that’s how she was entitled to various government benefits,” Brill says. “Apparently there was a breakdown somewhere in the line seeing how these kids were being raised – you would think if you were getting the benefits, at some point someone would do a home visit or something to determine face-to-face what was going on. Maybe that did happen, I don’t know.”

Susanne was also homeschooling the kids, but it’s unclear whether she submitted the required paperwork to the school district. Brill says, “If you don’t tell the district you’re homeschooling your kids then it would require a complaint from someone, either children’s services or the district itself, to make a truancy determination or a child neglect determination.”

Can the boys go back and press charges now that they’re adults?

Brill says if the children feel their father has abused them, they have the option of going to the police or the district attorney.

“There are statutes of limitations,” Brill says. “For example most felonies are five years and the average misdemeanor in New York is one year. So if this happened in the past five years and rose to the level of a felony, if they could get the police department or district attorney’s office interested,” they could potentially press charges.