Explain how crossing over, the distribution of random mixes of homologous chromosomes into gametes, and fertilization all contribute to variation in the traits of offspring

When homologous chromosomes in meiosis are lined (during prophase I and materials I) for separation to daughter cells, the chromosomes arms may form a synapse and exchange genetic material. This results in gamete cells having recombinant alleles. When fertilization occurs, two haploid gametes from different individuals fuse to form a diploid cell that has genetic traits from both the parents.