Dr. George Graef, soybean breeder at the University of Nebraska has spent more than a decade improving soybeans for Nebraska farmers. In simplest terms, his job as a plant breeder is to cross parents that each possess desired traits and then carefully examine the offspring from these crosses for individuals that have inherited the desired combination from both parents. One of the reasons this description is an oversimplification of plant breeding is that many or most of the traits that all plant breeders (and animal breeders) work with are quantitative traits. The inheritance of quantitative traits is more complexly controlled than the traits we have used as examples so far in this course. In this lesson we will examine the genetic control of quantitative traits by using one of Dr. Graef's soybean breeding projects as an example.