Thank you, Roger. I am assuming that William was RC because his descendants were and I am as well. His birth year is not definite. His obituary in 1900 stated that he was 'about 74'. The church record for his death had him down as 76.. The Kentucky Census of 1900, which was taken just before he died, states his birth year as 1823, yet states that he was 79 years old, which doesn't calculate correctly. Census records always seem to have errors. This same census states that he had been in the US for 54 years.
If he did emigrate in 1846 and was from Co. Mayo, I am assuming that perhaps this was related to the Great Famine. I'm not sure if there is a website where one can search famine records.
Additional information--William married Ellen Swift, who according to the Kentucky Census of 1900 had been in the US for 50 years at the time. They lived in Pennsylvania for a while before moving to Kentucky. Their first child, Mary A., was born in Pennsylvania, and 10 months old at the time of the1850 Census. However, this would have to mean that Ellen Swift Clarke must have emigrated at least by 1849. The couple had two more children born in Pennsylvania before moving to Kentucky sometime between 1852 and 1854 when their fourth child was born.
Yes, I have had my DNA tested.