Indeed, if the blending theory were true, then everyone would eventually look about the same. Mendel decided to perform some crosses with his plants to test the blending theory. Whenever he performed such crosses, he always came out with these mathematical ratios. These mathematical ratios are very important because changes in ratios can sometimes be indicators that evolution is occurring.
Lets assign letters to each trait and perform some genetic crosses using a single gene.
Any time a big T is present, the plant is tall. When no big T is present, the plant will appear short. If any small factors were present, they would have certainly have shown up at some time during his observations of the parent and grandparent plants. Since each organism possesses at least one big T, and big T is dominant to little t, whatever effects may be produced by the little t are totally masked. All offspring in this cross express the dominant characteristic for tallness.