Complex sentence: Charles Russell's son was the famous American poet James Russell Lowell; his grandsons included the American Civil War hero Gen. Charles Russell Lowell and Boston banker and family lawyer William Lowell Putnam; and his great-great-grandson was the poet Robert Lowell.
Split into simpler sentences: Charles Russell's son was the famous American poet James Russell Lowell; his grandsons included the American Civil War hero Gen. Charles Russell Lowell and Boston banker and family lawyer William Lowell Putnam. His great-great-grandson was the poet Robert Lowell.