George Clooney is mourning the loss of his older sister, Adelia Zeidler, who died on Friday, Dec. 19, at the age of 65 after a brave fight against cancer.In an exclusive statement to People, the actor honored his sister, whom he affectionately addressed as "Ada.""My sister, Ada, was my hero. She faced down cancer with courage and humor. I've never met anyone so brave. Amal and I will miss her terribly."Adelia Zeidler, per her obituary, died at St. Elizabeth Healthcare in Edgewood, Kentucky, while "surrounded by the people she loved." The notice also praised her contribution to art education by teaching art at Augusta Independent School. The obit continued:"In high school, her academic achievements qualified her to be a National Merit Scholar. Her love for reading connected her with other readers in a local book club."Further, the announcement honored George Clooney's late sister's involvement in Augusta's community as a grand marshal of the state's Annual White Christmas Parade, as well as her active membership in the August Art Guild.A funeral will take place on Dec. 22.Adelia Zeidler: A glimpse into the life of George Clooney's private sisterBorn on May 2, 1960, Adelia Zeidler was named after her great-grandmother. Their parents are journalist and anchor Nick Clooney and writer Nina Bruce Warren.George Clooney's sister also attended college in Louisville and Northern Kentucky and worked as a bookkeeper. While her brother enjoyed fame as an actor, Adelia Zeidler remained in Augusta and kept a private life.Nevertheless, the Ocean's 11 star once shared rare insight into his bond with his sister. In an interview with The Tennessean in 2019, George Clooney revealed:"All the things we see on cable news of people being unkind to one another doesn't exist. They have to get along. I was really lucky to be raised in a small town like that."Per Hello! magazine, the siblings were close growing up and belonged to the same group of friends because of their close age gap. Their mother, Nina Warren, spoke about George and Ada's closeness in a 2006 HGTV interview:"I came home from work one day and George and our daughter and several friends were having a party in [a room of our house]."She went on, narrating:"They had taken [marshmallows], and they would lick one side of them, and throw them at each other. When I came in, there were marshmallows stuck all over the room."Adelia married Norman Zeidler, a retired army captain, in 1987.At their wedding that took place in their hometown, George read the scripture, while their aunt Rosemary Clooney serenaded the newlyweds with a romantic tune.Nina also once spoke about the union, expressing her gratitude to the Kentucky community."The whole town helped with the wedding. We couldn't have gotten through it without them."Meanwhile, she is survived by her brother, their parents Nick Clooney and Nina Clooney, and her children, Nick Zeidler and Allison Zeidler Herolaga.