Complex sentence: He and other critics essentially discounted Hemings memoir, while attributing to him a range of negative motives for telling his story, but the 20th-century historian Merrill Peterson noted Hemings' details about events early in his life were mostly accurate.
Split into simpler sentences: He and other critics essentially discounted Hemings'memoir, while attributing to him a range of negative motives for telling his story. But, the 20th-century historian Merrill Peterson noted Hemings' details about events early in his life were mostly accurate.