If both parents contribute equally to the genetic information of the child, how can the chromosome number in humans remain constant for generation after generation? There is a specialized kind of cell division that results in the formation of sex cells. In this chapter, we will discuss the mechanics of this process. Knowing the mechanics is essential to understanding how genetic variety can occur in sex cells. This variety ultimately shows up as differences in offspring as a result of sexual reproduction.

Sex and your sexuality influence you in many different ways throughout life. Before birth, sexdetermining chromosomes direct the formation of hormones that control the development of sex organs, after which the effects of these hormones diminish. With the start of puberty, renewed hormonal activity causes major structural and behavioral changes that influence you for the remainder of your life.

These structural and behavioral changes are also directly affected by your diet. You truly are what you eat. The chemicals we call food undergo reactions that convert them into components of cells, tissues, and organs. A better understanding of foods, dietary requirements, and how the body processes foods can be helpful when selecting healthful combinations and hopefully will improve your lifestyle.