Legal Question in Family Law in California

I laughed so hard when I first read this. I thought from your misplaced modifiers that you snuck in one night and got her pregnant without her knowing. If you are married, you are presumed to be the father. If you are not married, you would have to establish paternity through a petition filed in the court. It wouldn't be without her knowledge, because she would have to be served with the papers, and either answer or default. The birth certificate is irrelevant.