All cells except for the sperm and the egg go through mitosis (asexual reproduction). The sperm and egg go through meiosis (sexual reproduction). During mitosis, crossing over occurs. Crossing over between homologous chromosomes creates patchwork of genes from both parents. Crossing over is the exchange of chromosomes segments during prophase I of meiosis I. For example. If the mother is a red chromosome and the father is a blue chromosome, the crossing over process would get the mother chromosome part of the father blue and vice versa.