Answer:
Three events in sexual reproduction that contribute to genetic variation include crossing over, in which the sister homologous chromosomes of a cell exchange genetic material through recombination of genes. Another event is independent assortment or random fertilization, as there are numerous variety of ways that the chromosomes of the gametes can combine, after meiosis, through fertilization to form a zygote. The third is mutation, in which on rare occasion, there is a slight and random change in the genes of a gametic cell caused by environmental factors.
