My great-great-grandfather Jeremiah Flynn is reputed (no written record)to have come from Keel, Castlemaine to Glenlough, Castlegregory with his brother Michael. Michael occupied the farm in 1850 (and probably earlier). Jeremiah married Catherine Lynch in Keel in 1853. Jeremiah is listed as the farm occupier in 1861 and the line is clear from there on. I have nothing on Michael other than his name in Griffith's Valuation as occupier of the property in 1850.
I have searched the Castlegregory parish records without success for anything on Michael (marriage, birth of children). I also have not seen an entry for your Michael born c. 1838 or any entry for Michael Flynn and Johanna Kean/Keane (marriage or baptisms of children). There were Keane families in the area at the time and also a number of Flynn families.
What is your source for the birth place of Michael b. 1838. Do you have anything on siblings. Where did he go to ?
Castlegregory parish records (marriages and baptisms) started in 1828 but names of fathers of the bride and groom were not recorded until 1864.
Contact me privately if you wish.