There are plenty of conflicts that have created generations of hostilities. Sometimes the people have even forgotten why they're supposed to hate those other people. After the Civil War you could find the children and grandchildren of Southerners who resented the North's victory. Those children and grandchildren never fought in the war. Then you have conflicts like those between the Irish and British, where Irish-Americans supported the Irish cause even though their families have lived in America for generations and have never set foot in Ireland.