John passed away peacefully June 24, 2019 at Bronson hospital. Born in Canton, OH, August 12, 1924, he was the second son of Harold (Grace) Lewis Sinclair. At age 16, John moved to Kalamazoo because his father was hired by the American Cyanamid Company. In Kalamazoo he attended the old Kalamazoo Central High School where he met his true love, Joan M. Rothlisberger. He served in the US Army, turning 19 years old on the ship to Europe. He attained the rank of staff sergeant during his service. After surviving a long separation during WWII, he and Joan were married on July 20, 1946. They moved to Ypsilanti, MI where John attended the University of Michigan School of Dentistry while Joan taught 1st grade. After his graduation they returned to Kalamazoo to raise their family. John became very active in the Kalamazoo Valley District Dental Society, and later with the Michigan Dental Association. He practiced dentistry for over 60 years and loved his profession, 30 of which were in practice with his son, John Jr. He served as President of the Kalamazoo District Dental Society for four years and as Secretary/Treasurer for 12 years. He served as a board member at the University of Michigan School of Dentistry. He was presented the Edgar Honey award by the Kalamazoo Valley District Dental Society, the highest and most prestigious award in his profession, for a lifetime of achievement and caring. He traveled the world extensively with family and friends. He also enjoyed tennis and golf for many years. He is preceded in death by his wife of 63 years, Joan, and brother, Alvin R. Sinclair. Surviving are his children, Susan (Gene) Haulenbeek, and Dr. John (Debbie) Sinclair, both of Kalamazoo; his grandchildren, Todd (January) Haulenbeek of Kalamazoo, Steven (Bridgette) Haulenbeek of Chicago, IL, Carrie (Bryan) Dall of Kalamazoo, Sarah (Robert) Brandao of Ellicott City, MD, and Rebecca Sinclair of Grand Rapids; great-grandchildren, Jonah, Ella and Sophie Haulenbeek, Addison, Tessa and Rory Dall, all in Kalamazoo and Frank Haulenbeek in Chicago; several nieces and nephews; and special friend, Jeanne Tindall. John was truly an amazing and generous man, friend to all, role-model to many, and hero to some. He will be remembered for his warm and amiable personality and his compassionate attention to so many. As the patriarch of an ever growing family, who loved and revered him, he will be missed beyond what words can express but he has left an indelible mark behind as well as a standard for many to aspire to. At the request of the family friends may visit between 4 and 7PM on Friday, June 28 at Langeland Family Funeral Homes Burial & Cremation Services, 3926 S 9th St, Kalamazoo, MI 49009. Services to celebrate John's life will be officiated by Pastor Steve Charnley on Saturday, June 29 at First United Methodist Church, 212 South Park St. Kalamazoo, MI at 11:00AM. Interment will be in Mountain Home Cemetery. Contributions may be directed to Talons Out Honor Flight or the University of Michigan School of Dentistry. To view John's personalized guest book, please visit https://www.langelands.com.