Typically, 50-70% of the people who share a surname are not biologically related. In other words, half or more of the Parrs' you meet are not yours. If you want to build your personal family tree I suggest you purchase a membership in ancestry.com. Or, if you have the time, visit your genealogy section at the local library. New York and especially Long Island has many sources of information.
If you want to potentially build an instant Parr family tree, go to the Parr DNA site and follow the directions to complete the simple mouth swab test.
My Parr family left Southold, Suffolk, New York (Long Island for other readers of this message) before the Revolutionary War and migrated to Roxbury, Morris County, New Jersey among other places. Since then, we are many places.