The answer is exchange of genetic material between homologous chromosomes. Homologous chromosomes are comprised of chromosome sets of around a similar length, centromere position, and recoloring design, for qualities with the same comparing loci.
In genetics, random fertilization is a situation where fertilization occurs randomly with many possible outcomes. The fact that random fertilization has a large number of possible outcomes means that the resulting product can have a wide range of characteristics. This gives a rise to a great variation in the genetics of the product.
