Sean Astin Shares Touching Throwback Photo Of His Late Mom, Patty Duke

Actor Sean Astin honored his late mother Patty Duke with a touching throwback photo on Tuesday. The actor posted the picture on Facebook in the hours following the news that the Oscar-winning actress died at the age of 69 .

The 45-year-old actor, who is best known for appearing in "The Goonies" and the "Lord of the Rings" franchise, wrote "I love you mom" and later updated the post with his family's official statement.

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. We celebrate the infinite love and compassion she shared through her work and throughout her life.

Her work endures...
The Patty Duke Mental Health Project .

Sean was adopted and raised by Duke's third husband, John Astin, but he also considers Desi Arnaz Jr. -- the son of Lucille Ball and Desi Arnaz -- and Duke's second husband, Michael Tell, to be his fathers. 

According to ABC News, Duke married Tell as a way to avoid the scandal of finding herself pregnant by Arnaz Jr., who was just 17. The marriage lasted only 13 days and Duke would go on to marry John Astin in 1972. Believing Arnaz Jr. to be his biological father, Sean struck up a relationship with him only to learn years later that Tell was actually his biological father. 

"Desi Arnaz Jr. loves me, and I love him. We are so close," Sean said in an interview with "20/20" in 2004.  "Science tells me … that he's not my biological father. Science tells me that Mike Tell is."

The actor went on to say that he has close relationships with all three men and his stepfather, Mike Pearce, who Duke married in 1986.

"I can call any of them on the phone any time I want to. John, Desi, Mike or Papa Mike … my four dads," he said. 

In that same interview, Sean and his brother Mackenzie opened up about what it was like growing up with their mother in the years before she was diagnosed with biopolar disorder. The brothers recalled painful moments characterized by their mother's instability -- incidents they describe as "freakouts" -- but Sean was quick to say things weren't always that bad. 

"This woman is a powerful, strong woman, who wanted us to grow up independent and confident and strong … 99 percent of the time," he said.