Is there any genetic testing that can definitively tell if two people are related?

Contact FamilyTreeDNA and discuss it with them. You will find them on the web. I know the real value of genealogy DNA testing is if the company you choose has cousins of yours going back several generations in their database and they are allowed to notify you of those cousins and you make contact with them you can collaborate information. They might have discovered ancestors you haven't and you might have discovered ancestors they haven't. So if they find cousins for people they might find that you 2 are related.

However, have you thought about good old fashion traditional genealogy research for both of you. Just because your family is on the east coast and his is on the west coast doesn't mean a thing. Americans have been moving west for years and some have gone back east. Any one American very likely has cousins unknown to them at various points throughout the country. Now having the same surname does not necessarily prove or indicate you share ancestors.

Anytime you wish to trace your family tree, check the resolved questions about finding your family or researching your family tree.

Good Luck!

Is there any genetic testing that can definitively tell if two people are related?

Ever heard of a paternity test? The problem is people who aren't related can still share genes. It's not like your family's genes are unique on the planet. Members of a racial group all descend from a common gene pool. If you go back far enough, we're all related.

My great great great grandmother came over long ago. In looking for her I found another family with the same last name and they went far north. I have no idea if we are related but it is a strange name. In finding their graves, there was an unkept grave with a 15 year old boy with that last name...and I wonder if we are related. In searching names I find that last name to be very popular in Australia and would like to do more research to find out if I am related.