Yes! It is feasible to conduct a DNA "paternity test" without directly involving the father by using probable or known siblings. In these sibling tests, the DNA of two people who have the same biological mother is compared to see if they share the same biological father. If one brother's DNA matches the son's DNA and another brother's DNA does not match the son's DNA, then the second brother must be the father. Sibling tests can identify fathers who would otherwise go undetected. The only requirement for a paternity test to be valid is that the individuals involved understand what type of test is being done and give their consent. There are several different types of paternity tests, all with different levels of accuracy in determining genetic paternity. For example, the traditional blood test requires a sample of blood from each individual involved in order to compare genes. However, this type of test cannot distinguish between multiple fathers, and is therefore not recommended for use with siblings. Genetic testing using DNA markers found within the genome is now available for paternity purposes. These types of tests can accurately determine genetic paternity without the need for direct contact with the father. They are also useful when the father is unknown or unwilling to provide a sample. Siblings can help resolve issues related to paternity fraud, which is when someone pretends to be the father of her child in order to gain access to benefits that come with being a parent.