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 …