I'm assuming you're from the US based on your post. If so, you should be able to obtain a copy of your birth certificate online directly from the state you were born in for a small fee. Search online for "(your state) vital records." No shitty relative interaction required.
The passport thing for a child with absentee parents is a bit more difficult but can be done. I believe you need either a notarized affidavit or court order to accompany the child's passport application. Good luck.