Gene Tunney's parents were Mary Jean (aka Rose) Lydon and John Tunney. Both of his parents were born in Mayo, Ireland, near Kiltimagh, and moved to New York City.

He won the heavyweight boxing championship from Jack Dempsey in 1926 and successfully defended his title against Dempsey in 1927. In 1928, he successfully defended his title against Tom Heeney and then retired from the ring undefeated in 1928. He then married Andrew Carnegie's great niece, Mary Josephine Lauder (aka Polly) in October, 1928, went on an extensive honeymoon, then returned to the U.