The independent assortment of chromosomes in the first meiotic division, often leading to new associations of alleles, is a fundamental kind of genetic recombination. If two characteristics always segregate together during meiosis, though, then only two kinds of gametes result. Genes present on the same chromosome do not generally assort independently except through crossing over. Linkage of traits because their genes are located on the same chromosome leads to exceptions to the law of independent assortment.