DNA analysis. Computer artwork of a molecular model of DNA (deoxyribonucleic acid, left), two DNA double helices (across centre) and a chart showing the results of a DNA test (upper centre) known as DNA fingerprinting. The letters A, C, G, and T (lower right) represent nucleotide bases. These are units within the DNA molecule, arranged in a specific order to 'spell out' a gene. Genes are instructions that determine the structure, function and behaviour of the cells in a living organism. They are inherited by each generation, making it possible to identify a child's parents. The pink and blue double helices may represent DNA from the mother and father while the chart may represent a paternity test.