Paternity testing. Computer artwork of the procedure involved in a baby's paternity test. A sample of DNA (deoxyribonucleic acid, far left) is taken from the baby and its parents. The genetic code formed by the four bases (yellow, blue, green & red, bottom right) on a section of this DNA is revealed by a process called electrophoresis. The DNA bands are transferred onto an autoradiograph (white sheet) for comparison. The baby's DNA comes partly from each parent as the father's sperm fuses with the mother's egg (bottom left). Therefore any of the baby's DNA bands, or genetic markers (blue rectangles, top left), which do not match those of its mother must match its father's.