I have an adopted child. He is my son. A paternity test will not set your mind at rest. It will only tell you if on the day she got pregnant, she had sex with you. It doesn't tell you about any other days. You need to have trust. If you don't trust her, then you need reassurance. So talk to her. Dialogue on the subject of trust. Here's one out of the book, "What do I see as the greatest obstacle to trust in our relationship? How do I feel about my answer?" Or you can frame your own question. But not dealing with problems does not make them go away.