 So now we're going to get ready to go through some polygenetic inheritance problems. These are practice problems that I've come up with, just kind of combining a lot of different sources to try to come up with the best way to help you understand how to kind of divide up and conquer these problems. They can seem really overwhelming and intimidating if you look at the big picture. But if you go step by step with these simple calculations, I promise these are going to seem like a breeze. So first let's explain what polygenetic inheritance is. It seems like such a big word with no real backing behind it that we haven't talked about. So thinking back to Mendel, we went over the inherited traits that were governed by either a type of dominance or a combination of dominance, like flower color, pea pod color and texture. Lots of these traits that we talked about vary in population because of the phenomenon that's known as polygenetic inheritance. This phenomenon is a result of additive effects from multiple genes, meaning that things like height, eye color, skin color are all coded for by varying alleles on different chromosomes. So all of those dominance and recessive alleles need to be added together to create your overall picture of what that person's height, eye color, skin color will be. So when we talk about polygenetic inheritance, the words dominant and recessive are in quotation marks because the pairs of alleles are not truly dominant, nor are they truly recessive. Like we talked about when we went through the pea plants, how it was either wrinkled or round, where it was yellow or green, where the flower was red or white. These are not truly dominant traits, they're more of an additive blending type traits where one allele will add to another to create its overall phenotype. So there are lots of different ways you can solve polygenetic problems, tons of solving apps all over the place, but there's two simple calculations that I find the easiest to understand, which is going to be either the rules of probability or binomial expansion. Using the combination of these two techniques are going to be the quickest and easiest way to find the answers to polygenetic inheritance problems. So by doing these math problems, you're going to cut down on the amount of errors that you will make.