Legal Question in Family Law in California

I'm assuming you mean when she files for child support for a child from a man she was not married to when the child was conceived. The technical answer is "no," but the practical answer is "yes." The law requires that the mother prove the man is the actual father in a paternity action (unless they both sign a voluntary declaration of paternity and file that). That does not mean absolutely a DNA test is required. For example the man might admit on the witness stand he is the father. In reality, however, DNA tests are so simple, so painless (yes they really can just swab the inside of the baby's cheek and the man's), and so conclusive, that it is pretty much always the way paternity is proved.