In the nineteenth century, around Gregor Mendel’s time, the blending theory was the commonly held belief that characteristics were mixed in each generation. For example, breeding two horses, one with a light-colored coat and the other dark, would result in offspring that would have an intermediate coat color. If this held true, then eventually all organisms would become more alike in each generation. Although this theory persisted for many years, it was eventually supplanted by the work of Mendel and other modern geneticists.