During prophase I of meiosis, homologous chromosomes cross over and contribute genetic information from the mother and father cells. When this happens, the resultant haploid cell contains its own genetic information.
Three chance occurrences during meiosis contribute to the daughter cell's genetic diversity. First, there is a random pairing between male and female gametes. As each has its own genetic makeup from the meiosis process, and each makes a contribution to the next cell, this results in unique information. During meiosis, homologous chromosomes cross at prophase I and pair up during metaphase I. As part of prophase I, the homologous chromosomes share genetic information. As a result, there are four unique chromatids. The chromatids randomly divide then randomly realign, resulting in genetic diversity.
The process of male and female gametes exchanging information is called genetic recombination. As it is difficult to limit the unique combinations of genes that pass from male and female gametes to their daughter cells, this promotes genetic diversity among organisms. Because the chromosomal number reduces from diploid to haploid during meiosis, 23 unique pairs of chromosomes have to form. All of this takes place over four main meiosis I stages: prophase I, metaphase I, anaphase I and telephase I and cytokinesis. Meiosis II then follows.