I can't be of much help with your family tree, but I share the same last name as well. I've heard that the name somewhere down the line originates from Galway, and that it used to be something like O hoireachtaigh, but I haven't seen anything like that on here. There is also variations like Heraughty, harrity, and many others too. I haven't seen many heraty's, but my family lives in california too. I hope you find out more about the names history. Goodluck,