How does a paternity test work?

Answer 1

Every human has a unique sequence of DNA, but a lot of it is the same, as that is essential to our survival. The portion that is unique, however, can be mapped out. Half of it will be from your father and the other half from your mother. If the portion that is unique can be shown to be 50% like someone else, you are related to that person by one generational step (parent-child). In the same way, you can determine your grandfather, who should have 25% similarity. Mutations occur, but these are generally small enough that they do not affect a paternity test. It is the same mutations, however, that have built up over thousands of generations of your ancestors, resulting in the unique DNA segments your family has in the first place. On average, each human being's genome contains about 128 mutations at birth (out of 3.2 billion base pairs). For more information, see the page link, further down this page, listed under "Related Links."