My grandmothers birth certificate has no father listed although her mother married  3 months later. Is there a way to determine if the man she wed is my grandfather? My great grandmother went on to have 15 more children in this marriage  after my grandmother was born.

I have found with my DNA matches, I can start sorting them by maternal and paternal and sometime if the other people are real good I can even get great grandparent lines matched.  With enough matches and good trees with the match, you should be able to find your paternal line.

Thanks Steve. I was able to find a DNA match between myself and my greatgrandfather's mother so I am assuming the man she married is my greatgrandfather. BUT why was he not listed either on the baptism or the birth certificate. BTW they went on to have 16 children total including 3 sets twins.