In 1931, psychologists Winthrop and Luella Kellogg began one of the most unusual and controversial experiments in history. Their question was simple but bold: Could nurture overcome nature? Could a chimpanzee develop human-like behavior if raised exactly like a child? To find out, the Kelloggs brought a seven-month-old chimp named Gua into their home and raised her alongside their ten-month-old son, Donald, as if they were siblings. Both were treated the same—fed at the same time, dressed in sim