How Genes Effect Our Appearance In 1865, an Augustinian monk named Gregor Mendel discovered that individual traits are determined by discrete "factors," later known as "genes," which are inherited by the parents. While researching his new discovery, he found that genes come in pairs, and each gene has a trait with two alternate forms, such as the pea plant with it's green or yellow seeds. By analyzing the results of various crosses, Mendel concluded that each …showed first 75 words of 902 total…

…showed last 75 words of 902 total…male cells. A matched pair of X chromosomes is found in female cells. Thus, XX chromosomes determine femaleness, and XY chromosomes determine maleness. Females produce eggs with X chromosomes; males produce sperm with an X or Y chromosome. It is these X and Y chromosomes, as well as genes, that determine what we will look like, based on the dominant and recessive traits, as well as the X or Y chromosome produced by the male.