Long before Mendel and other formal theories of inheritance and genetics were proposed, it was commonly held that inheritance was based on the idea of blending. Inherited traits were believed to be an average mix of parental traits. So, for instance, crossing a red flower parent with a white flower parent would produce a pink flower. A very tall plant crossed with a very short plant would produce a medium-sized plant. However if this concept of blending inheritance were accurate, it would eventually lead to one flower color for a particular flower and one plant height for a specific plant. This has not happened as we still see tremendous variation. In addition, the hypothetical theory of blending inheritance does not account for certain traits disappearing and then reappearing such as a red-haired child being born from a blond-haired mother and a brown-haired father.