In recent years, there has been an explosion in the use of DNA testing. There are three reasons people do a DNA test – one is a legal DNA test which involves two individuals being tested for proof of a relationship, commonly used to prove paternity. Another form of testing is genetic health testing which is used to establish if a person carries genes that involve health risks such as genetic disorders, cancer or heart disease. The third type of test, which this PDF article focusses on, is genealogical DNA testing – a relatively new technology where customers send their sample (saliva or cheek swab) to one of the testing companies to have their DNA extracted and analysed.