All About Sean Astin's Famous Parents, Patty Duke, John Astin and Michael Tell

'The Lord of the Rings' star Sean Astin loves his big, blended family

Sean Astin, star of fan favorites like The Goonies, The Lord of the Rings and Stranger Things, comes from a Hollywood family.

The actor grew up with The Addams Family's John Astin as his father and The Miracle Worker’s Patty Duke as his mother but when Sean got older, Duke revealed that John wasn’t Sean’s biological father. John had adopted Sean when he was very young shortly after he married Duke. At first, the actress told Sean that his biological father was Desi Arnaz Jr., son of I Love Lucy’s Lucille Ball and Desi Arnaz. Later, DNA tests revealed that Sean’s father was music promoter Michael Tell.

"If you want to know who I am, John Astin is my father, Michael Tell is my biological father,” Sean told PEOPLE in 2001. He’s close to all three men and considers them all family — Sean also has a good relationship with Duke's fourth husband Michael Pearce.

“I have a good relationship with Mike. That’s who I am,” he added. “I don’t fault anybody, I don’t fault myself or Desi, who is like my godfather, I have such a powerful love bond with this man, he’s a gorgeous human being.”

Related: Who Is Sean Astin’s Wife? All About Film Producer Christine Astin

Despite having an unusual path there, Sean told PEOPLE in 2002 that he was in a good place with his family. “My feeling is that I want to honor my relationships with the people who looked after me,” he said, especially John, “who gave a huge amount of his time, energy and love.”

Here is everything to know about Sean Astin’s parents: Patty Duke, John Astin and Michael Tell.

Duke was a child star

Although she was known to the world as Patty Duke, the actress' real name was Anna Marie. She got her big break playing Helen Keller in The Miracle Worker on Broadway and later reprised the role in an Oscar-winning performance on the big screen. Quickly after, Duke got her own network show, The Patty Duke Show.

In 1965, at age 18, she married Harry Falk, an assistant director on her namesake show. The couple separated in 1968 and their divorce was finalized in 1970.

During her career, Duke won an Oscar, two Golden Globes and three Emmys — she was also the president of the Screen Actors Guild for three years. Later in life, Duke was diagnosed with manic depression, now called bipolar disorder.

John and Duke met at a Hollywood party

When they met in 1964 at an ABC-TV convention, Duke and John were both bonafide celebrities. She had already won an Academy Award for her portrayal of Helen Keller in The Miracle Worker, and he was starring as Gomez Addams in The Addams Family. They reconnected in 1970 at a Universal Studios wrap party, and sparks flew.

“We were able to communicate very quickly with each other,” John told PEOPLE in 1977.

When they reconnected, 40-year-old John was still married to actor Suzanne Hahn, and 23-year-old Duke was newly divorced and dealing with a complicated romantic situation with Arnaz Jr., who was 17 at the time. While they were involved, his mother, Lucille Ball, allegedly opposed the relationship.

Related: All About Lucille Ball and Desi Arnaz's Children and Grandchildren

Duke quickly discovered she was pregnant, but the baby’s paternity was unclear. Sean was born on Feb. 25, 1971, while she and John were still keeping their relationship quiet. “There was a lot of stuff in the press early on,” John told PEOPLE in 2001. “[Sean] basically grew up without any real knowledge of all that stuff.”

Duke and John married in 1972

Duke and John married in the garden of John's parents’ home in Bethesda, Md. on Aug. 5, 1972.

“He promised me a rose garden,” Duke told PEOPLE in 1977, “and I got one.” When they wed, she was 25 and he was 42 — Sean was 18 months old.

“You have to understand that the family is more important than anything in life," John said, reflecting on their relationship.

They adopted each other’s children, and welcomed a son

John had three children from his marriage to Hahn — after he and Duke married, she adopted his kids, and John adopted Sean. The couple welcomed their son Mackenzie Astin on May 12, 1973. Like his brother, Mackenzie is also an actor, who rose to fame on The Facts of Life and has appeared in shows like You, Scandal and The Magicians.

Even after they divorced, Duke remained close to John's children. “They are all good boys, and by ‘good’ I mean people who care about how other people feel,” she told PEOPLE in 1985. “David, the oldest, is 26 and works in the computer industry. Allen, who is 24, has traveled to India and is a follower of the teachings of Baba Muktananda ... We have wonderful discussions. My 20 year old, Tom, is starting UCLA."

When Duke died in 2016, Allen wrote a blog post about life with his adopted mother. “My big family has its share of craziness and dysfunction, yet it is so full of love and the desire to live life with passion that I am every day filled with gratitude for this mess,” he wrote. “This gift of my family, as it is today, is full of Anna’s life and she will always be a part of us.”

John and Duke divorced in 1985

Duke and John struggled with her mental health at home, but the end of their marriage came when the actor converted to Buddhism in 1984 and attempted to persuade his family to join him.

“We had gone as far as we could,” she said. The couple divorced in 1985 but remained close.

“There is a deep and abiding love between us, but we just don’t get along,” she told PEOPLE the year they divorced. “It’s sort of like fingernails on the blackboard. He does it to me and I do it to him. We even laugh about it sometimes because it’s so absurd."

When he was 14, Duke told Sean that Arnaz Jr. was his real father

Sean grew up believing John was his biological father, but when he was 14, Duke told him that his biological father was Desi Arnaz Jr. He later found out that that was not true, but the two developed a deep bond nonetheless.

"Desi Arnaz Jr. loves me, and I love him. We are so close," Sean told ABC in 2004. "Science tells me that he's not my biological father. Science tells me that Mike Tell is."

Sean discovered his biological father in his 20s

Duke and Sean's biological father, Tell, only knew each other briefly in 1970, when he sublet her apartment. She later described him as a “total stranger.” During one of Duke’s self-described manic episodes, the couple eloped, and the marriage was annulled after 13 days.

Years later, after a relative of Tell’s suggested the promoter might be Sean’s father, the actor underwent a DNA test in 1994, with John, Arnaz and Tell. The result was that Tell was his biological father and Sean soon developed a relationship with him.

"I can call any of them on the phone any time I want to," Sean explained to ABC. "John, Desi, [Astin’s stepfather, Duke’s husband] Mike or Papa Mike ... my four dads."

To John, genetics were immaterial to their bond. “The greatest treasures are the treasures of the heart and Sean is a treasure,” he told PEOPLE in 2001. “We’re very close, we have a good time together.”

He has also grown close to Tell. “His biological dad turns out to be a great guy and we’ve become friendly,” John added. “He’s a good guy.”

Duke became a mental health advocate

In 1982, Duke was diagnosed with manic depression (now called bipolar disorder) and she opened up about her mental health in her 1987 memoir, Call Me Anna. Sean later said it was groundbreaking for a celebrity to be so candid with a personal struggle.

“In the mid-'80s, when she ‘went public’ with her diagnosis and sharing her story about her mania and her depression and all that, I don’t know how many actors or celebrities had done that," Sean told Good Day LA in 2016. "I would say that the world now is infinitely more understanding and compassionate, and yeah, there’s still stigma, but it’s a different world out there. And, I think she had a nice role to play in that evolution of our society, so we’re all very proud of her for that.”

Growing up in a household with a mother who had bouts of mania and severe depressive episodes, Sean told PEOPLE in 2016, “wasn’t always pretty and it wasn’t always fun. But there was a lot of love.”

“There was never a moment of doubt that she loved me,” he added. “We were all in it together. We were all in the storm together.”

Duke died in 2016

Duke died after an illness on March 29, 2016. She was 69.

On his Instagram, Sean posted a photo of his mother holding him as a baby, and wrote in the caption, “This morning, our beloved wife, mother, grandmother, matriarch and the exquisite artist, humanitarian, and champion for mental health, Anna PATTY DUKE Pearce, closed her eyes, quieted her pain and ascended to a beautiful place.”

After her death, Sean has gone on to champion the mental illness advocacy his mother was so passionate about.

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