We live in different cities. We are not giving our specimens at the same time. I have black hair and brown eyes. The test can be done without the mother. But if the mother is not tested it is necessary to do additional testing in order to achieve that level of accuracy.
Children receive half of their DNA from their mother and half from their father.
By comparing the mother and child's DNA we can tell which parts of the child's DNA came from the mother, because they match exactly. So even if the tested man is matching part of the child's DNA, we don't know if he is matching parts that came from the biological father, or from the mother. Without the mother, there is a greater chance that even if the tested man is matching the child's DNA the matches could be random and the man might not really be the child's biological father. Yes, but it is usually not a good idea. One way is to test amniotic cells for the child's specimen.