Researchers interested in the physical locations of genes that influence a person's alcohol-related behaviors can use a method known as quantitative trait loci (QTL) mapping to identify the approximate locations of genes in the genome. QTL mapping can use recombinant inbred mouse strains, which are sets of inbred strains derived from cross-breeding the offspring of two genetically distinct parent strains. The inbred strains exhibit different patterns of the parent strains' genes. QTL mapping involves comparing alcohol-related behaviors in these strains and identifying patterns of known genetic markers shared by strains with the same behaviors. The markers allow the identification of probable locations of genes that influence alcohol-related behaviors. These locations can then be verified using other tests, and specific genes can be sought there.