The rearrangement of segments of genes or other DNA sequences. It occurs when reproductive cells (gametes) are formed, consequent to the independent assortment of parental sets of chromosomes and exchange of chromosomal material (see crossing over) that occur during meiosis. This results in offspring that have a combination of characteristics different from that of their parents. Recombination is also crucial to generating the huge diversity of receptors found on cells of the immune system and their corresponding antibodies. Hence during B-cell development a recombinase enzyme splices together random segments from a large gene cluster to create functional immunoglobulin genes for the light and heavy chains of the B-cell receptors. Because of the vast number of possible combinations, each progenitor cell and its clone of daughter cells is likely to have a unique antigen specificity. A similar mechanism accounts for T-cell diversity. Recombination can also be induced artificially by genetic engineering techniques.