Finding the truth may be really hard, as Kelly is such a common name. I had a family story told to me by my Aunt in Washington state, and later heard a similar story by someone in Toronto (they had never met each other). So the story was passed on, but later found out not to be true.
Unfortunately, you may have to just search backwards, starting with your Grandmother and her parents. Start by finding your Grandmother in the census, you can search at www.familysearch.org for free. If you need help knowing how to start, someone here can help.