Unless he or she is an identical twin, each person's DNA is unique. However, because you share more DNA with your siblings and half-siblings than with people who are not related to you, DNA testing can assist you in identifying them. However, just sharing DNA with someone does not prove that person is a sibling. For example, two people could have the same genetic mother and father without being siblings. In addition to identical twins, people often assume that siblings must be born to the same mother and father. This is not always the case - adopted children can have siblings. In fact, about one in every 200 babies is adopted. Also, there are situations where both parents may die before their children are old enough to understand what has happened - for example, if the parents die in a car accident while on their way to pick up their young children for a day at the park. In this case, the kids will go to live with the closest family member (usually a grandparent) until they are old enough to decide for themselves who they want to live with. There are two types of DNA tests: parentage tests and genealogy tests. A parentage test determines whether you are the biological child of your parents by comparing your DNA with those of your parents. This type of test can help you determine whether you should have been included in any wills or estate plans.