How can I find out who my great grandfather was?

Question:

How can I find out who my great grandfather was?

My grandfather's father is not listed on his birth certificate. My great grandmother is dead and no one in the family seems to know who the father was. Does anyone have any suggestions?

Best Answer - Chosen by Asker: Look who's shown as his father on your grandfather's death certificate instead. You can also see what's on his marriage license / certificate, and what he put down when he applied for a social security card for "father". Did he do military service, if so check his NARA records. More than one way to try to skin that cat!