Concept 8 Sex cells have one set of chromosomes; body cells have two. 1  Children resemble their parents. 2  Genes come in pairs. 3  Genes don't blend. 4  Some genes are dominant. 5  Genetic inheritance follows rules. 6  Genes are real things. 7  All cells arise from pre-existing cells. 8  Sex cells have one set of chromosomes; body cells have two.