The Kilkenny County Ireland vital records are now partially online. Michael's family comes from this area, so I did some searches and found Bridget Cashin, his great-great-grandmother's, baptism on 15 December 1841 at Rosbercon, Kilkenny. The parents named are James Cashin and Johanna Wallace, the same as on her marriage record in Canandaigua, Ontario, New York in 1864. Rosbercon is on the border of Kilkenny and Wexford and it seems that Michael's family straddles that area. Wexford is not yet online.
Interestingly, Bridget's godparents were Thomas Cody and Mary Butler. I descend from the Cody's as well. Could there be a connection? Only time, more searches, and some luck will tell.