Biological Grandfather - Not sure where to start.

It's quite a long story, but here is a summary. When my mother was younger, her Mom cheated on my grandfather often. He loved her so he never left nor really even acknowledged that it was happening so my Mother and all of her siblings have my grandfathers name on the birth certificate. My grandmother eventually left her children behind with my grandfather and never spoke to them again. Now that I am older, my mother confided in me that my grandfather is not her real father but someone my grandmother was sleeping around with. No one knows his name and my grandmother is obviously not going to speak to any of us, nor would my Mother want anything to do with that woman. I would never consider someone else to be my grandfather but I am curious as to what ethnicity my biological one is and any medical conditions he may have had. Is it possible to just submit my DNA to a database and see what comes up? I have no information on him nor anyone to go to regarding his name. Thanks!