Collin Gosselin, one of the sextuplet siblings who starred on "Jon & Kate Plus 8," believes being "institutionalized" as a pre-teen dashed his dreams of enlisting as a Marine.

The 20-year-old, who is now living with dad Jon Gosselin as he prepares to go to college in the fall, revealed to Entertainment Tonight in an interview posted Tuesday that he "was discharged" from the U.S. Marine Corps this past year after training as a recruit.

"I was towards the end of training, very close to graduating. The paperwork was looked into, and they found out that I was in fact in an institution at one point in my life," he told correspondent Rachel Smith.

Gosselin also opened up about his experience being sent to a behavioral institute when he was "11 or 12." In recent years, he has spoken out about mom Kate Gosselin – from whom he's estranged, along with most of his siblings – being the one to send him to the facility for several years.

"I didn't know what was going on, where I was going," he told Smith.

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"That was the most scared I've probably ever been in my life," he continued. "(Kate Gosselin) came to visit me once; it was for about 30 minutes, and the entire time all she did was lecture me and tell me I destroyed our family."

In a 2016 interview with People, Kate Gosselin said Collin was "enrolled in a program that is helping him learn the skills he needs to be the best him he can be."

"Collin has special needs," she said. "[There's] a fairly fluid diagnosis of what those needs are, but he needs to learn certain strategies to help him deal with things. This has been a struggle we've had for a very long time, and it's one I've dealt with on my own. I've felt very alone in this. By the same token, it's not something that has only impacted me or him – our entire family has been impacted."

She also reiterated these claims in a statement she shared on Instagram in July 2023.

Kate and Jon Gosselin seemingly have had a contentious relationship since their 2009 divorce. Jon criticized his ex-wife's decision in a 2019 appearance on "The Dr. Oz Show."

"Kate institutionalized him without a diagnosis and then created a diagnosis," he said. "He did not need to be in an institution. Just because he was a difficult child did not mean he needed to be sent away against my will, against my rights. I did not know where he went. It took me two and a half years to find him. It took me another year to get him out."

Gosselin's siblings are Hannah, Alexis, Aaden, Leah and Joel, who all turned 20 in May, as well as twins Mady and Cara. He only maintains a relationship with sister Hannah.

"I love my siblings very, very much. I would never hurt them. I would never trash their names in the media," Gosselin said. "But what I do believe is that my mother is behind things that they say in the media. She's behind their opinion of me. I think if we knew each other today, we'd be good friends."

He still dreams of being a Marine but is also open to returning to reality TV, he said.