In meiosis, variation occurs, because each gamete (either sperm or egg) contains a mixture of genes from two different parent chromosomes in sexual reproduction. In other words, the genetic coupling of non-identical DNA takes place in meiosis. It results in an offspring, which has the genetic material of two different individuals. A new combination of genetic information is produced in the gametes. This ultimately results in a new and unique set of chromosomes.
Crossing over occuring during Prophase I and independent assortment of chromosomes occuring during Metaphase I increases genetic variation.