DNA testing is a scientific analysis that uses DNA to identify relationships between individuals. DNA testing is most commonly used to establish paternity and works by comparing the genetic material of a child to that of any adults involved. Because every person has a unique genetic fingerprint (apart from identical twins) DNA can be used to establish an individual’s identity and heritage. DNA testing starts by looking at the most basic most basic building blocks of human beings; the cell.
Our entire body is made up of cells, almost every one of which contains an identical set of DNA. The DNA content for all cells is contained in several connected units called genes. These are made up of 46 chromosomes or 23 pairs. Collectively our chromosomes are responsible for determining all our physical characteristics, from height to eye and hair colour.
All but one of the pairs of chromosomes is of similar shape and size and it’s this ‘23rd pair’ that determines the sex of the individual (and looks different depending on whether the person is male or female). One set of chromosomes is passed through the male sperm and the other half comes from the female egg, therefore the child inherits half its DNA from its mother and half from its father. By comparing how the DNA varies between a child and an adult it’s possible to establish the relationship between the two individuals.
Because the DNA sequence in every cell is identical DNA testing is simple and painless and there’s no need to take a blood sample. Procedures differ, but typically involve taking a cell sample form the inside of the cheek (with a swab) or using a single strand of hair. If the test is to satisfy personal curiosity the cell sample can be taken at home and mailed to the lab. However, if the results may later be used in court the sample must be taken by a registered doctor. The results are quick and have proven to be incredibly accurate, with less than one tenth of a single percent margin for error.