Hi Shari, I don't know if you've found the information you were searching for but I believe I have some records for the parents of Thomas Joseph Cullen, born 10 Mar 1889 in Duncormick.
His parents John and Johanna (néé Murphy) lived in Duncormick. John died in 1911 and Johanna in 1953. They had 6 surviving children in 1911. One daughter, Johanna, married Laurence Devereux in Rathangan in 1923 and they still have decendants in the area. Let me know if you are still searching and I'll share what information I have with you.
Alice