DNA really is the final word on whether 2 people are related or not, and whether paper research is correct or not. You would get a copy of your father's birth certificate so why wouldn't you get DNA tested? They are all just pieces of your puzzle. Family Tree DNA and Ancestry have great sales on at the moment and prices have never been cheaper, around 50% off, so why not take a look? You may just find some new connections or break down that brick wall. Unless you are afraid? Try

https://www.familytreedna.com/order-form.aspx?ty=1104&Gr...=

For Family Tree DNA or

http://dna.ancestry.com/buyKitGoals.aspx

for Ancestry. Ask me if you have any questions.