Glenn Close on Discovering Her Family's Genetic Component for Mental Illness and Depression

Jessie Close, the younger sister of actress Glenn Close, felt it was her "fault" when her son Calen was diagnosed with schizo-affective disorder a decade ago.

"I had struggled for years with my own mood swings and I knew intuitively I was responsible for passing along my flaws to my son," she tells PEOPLE.

As Jessie would come to learn after she was diagnosed with manic depression, it was not a "flaw," but part of her genetic makeup.

"On my mom's side, there was a lot of depression," says Glenn, 74, of her family's history with mental illness. "Her uncle had schizophrenia. Nobody ever talked about. I did know that her half brother had committed suicide and that her own mother was depressed. She was also depressed and took meds for it."

"It wasn't even on the radar when I was growing up," adds Jessie, 67. "No matter how I behaved, no one could ever imagine it was a mental illness. It just wasn't part of our conversation."

That all changed by 2010 when Glenn cofounded Bring Change to Mind, (BC2M) a nonprofit with a mission to raise awareness and end the stigma and silence surrounding mental illness.

RELATED: How A Sister's Cry for Help Led Glenn Close to Change the Way We Talk About Mental Illness

Seonaid B. Campbell/ Courtesy Bring Change 2 Mind

Maximillian Tortoriello

"My mother is what's called a mosaic and so she was able to pass the mental illness on," explains Jessie. "And I am a mosaic and I passed it to Calen unfortunately but his brother and sister are fine. So Calen and I got the big hit." (Schizoaffective disorder is a condition that combines the symptoms of schizophrenia and mood disorders.)

Together, mother and son have found a certain solace in knowing the genetic component of their illness. "That it's not because of your character, but your genetics — to have that insight is helpful," says Calen, 39.

According to Dr. Stephen Hinshaw, Professor of Psychology at UC Berkeley and the scientific advisor for BC2M, mental illness results from a complex interplay of genes and environment. "With anxiety and depression, genes contribute about one third of the risk, for schizophrenia, about two thirds and for bipolar disorder, above 80 percent," he says. Environmental factors, he adds, also play a part, such as "early trauma, life stress and positive vs negative mindsets."

Courtesy Calen Pick Calen Pick's artwork

Knowing this, says Hinshaw, "can help us see that mental illness is not a 'character defect.' Most of all, we need humanization through the telling of real life stories of coping and recovery."

Today, Calen and his mom share a deep sense of "camaraderie." "Calen is the first person I'll call when I'm not feeling well because we have a tight bond and he understands," says Jessie. They also connect in their ability to tap into the world's beauty, both in Calen's paintings and Jessie's photographs and writing. (Her 2015 memoir Resilience shares her story in more detail.)

RELATED: Gabourey Sidibe Says Her Battle with Bulimia Was a 'Self-Defense Mechanism' for Her Depression

Together, with Glenn, they have become advocates for mental health and speaking openly about the brain's complexities. Says Glenn, "Jessie and her son Calen have taught me," she says, "To see how they've struggled with their illness and lived fulfilling lives, I've learned it's part of the human condition."

Along the way, she has learned how we are all affected by the health of our brain. Over ten years ago, Glenn notes, "I went through a series of tests at Columbia and they said, 'You're depressed' and I thought I would not label myself as a depressed person but I think what I've lived with, probably a good portion of my life, is a low grade depression that can sometimes feel like a mist or a veil but you've gotten so used to living with it — that it's not something you think of much. I take a daily dose of anti- depressants, not a huge dose, and it helps."

Courtesy Calen PIck Calen PIck

Never miss a story — sign up forPEOPLE's free weekly newsletter to get the biggest news of the week delivered to your inbox every Friday.

Looking back on BC2M's ten years of work, she says, "We started it not knowing anything about what we were getting into and we wanted to stay authentic. And the fact that, I think we're safe to say, we're one of the major mental health organizations in this country, that's incredible and I'm so proud of that and the many people who work behind the scenes and our community."

After all, she says "It's natural thing to talk about."

PEOPLE and its Let's Talk About It Mental Health Initiative is partnering with Glenn Close and Bring Change To Mind, in an effort to destigmatize mental illness. A four-part virtual panel discussion series on mental health and young people through the lens of parenting, masculinity, race, LGBTQIA, and COVID-19, Conversations with Bring Change to Mind in Partnership with PEOPLE, will be moderated by PEOPLE's editor in chief, Dan Wakeford; during Mental Health Awareness Month and will stream from May 24-27 on PEOPLE.com, PEOPLE's YouTube, Twitter and PeopleTV's social channels, as well as on BringChange2Mind.org.

If you or someone you know need mental health help, text "STRENGTH" to the Crisis Text Line at 741-741 to be connected to a certified crisis counselor.