R. Sargent Shriver, the father of Maria Shriver and father-in-law to Arnold Schwarzenegger, has passed away at 95 years of age, CNN reports. Shriver was mostly known for his role in politics and social activism, working with President Lyndon B. Johnson, organizing the Peace Corps launch, as well as the Special Olympics, which was founded by wife Eunice Kennedy Shriver. Plagued by Alzheimer disease for the last part of his life, he was the subject of daughter Maria’s 2004 children’s book on the disease, What’s Happening to Grandpa?