Body cells--somatic cells--contain two copies of each chromosome. This number varies from species to species; for humans there are 46 total chromosomes, in 23 pairs. Each one of the pair has information about the same traits as the other one of its pair. The information may be different, but it is for the same trait. The individual received one chromosome of each set from either of its parents. For example, there are two copies of chromosome number three in each of your body cells--one from your mother, one from your father. In this way, you are a combination of the genetic information of your mother and your father. When your own body produces reproductive cells (eggs or sperm), you will pass on only one copy of chromosome number three--that you received from your mother, or that of your father. Each one of the pairs separates into an individual egg or sperm independently--producing an egg cell with chromosome number three from your mother has no relation to which one from pair number four or five or six goes into that particular egg cell. The resulting new embryo is a combination of chromosomes, one of each pair from you, and one from your partner. In this way, the new embryo is a combination of genetic traits of each parents.