I submitted my DNA to Ancestry.com, Family Tree and other organizations when it was initially offered. There is nothing to hide, no reason that I can see not to and there are many positives. A lot folks in my family also submitted their DNA. As a result, our mutual family histories have expanded greatly.
There is a lot of information about my family heritage because my ancestors were interested in this did and researched it and kept records. My grandfather was a member of the SAR and several of my aunts became members of the DAR.
My heritage is Irish, Scotch, English, French and Scandinavian. Some of my ancestors immigrated to America around the same time as the pilgrims. Obviously, at least a few fought in the American Revolution, hence the memberships in SAR and DAR.