as someone born in, and living in Dublin with about 75% Irish roots I suppose I should speak up!
The Fitzsimon branch from near Bray, Co. Wicklow - I've traced this side back to 1800ish, they married Doyles and Cantwells from Co. Wicklow.
The Sheridan branch from Dublin City, right back to shoe-makers and cabbies in the early 1800s, married to Dillons from Ballymaghrue, Co. Wicklow. This branch also includes Cathcarts (land steward) and Wilson from Kings County/Offaly - both of whom possibly originate in the North of Ireland. Also included in this branch is Hodges, my mysterious coastguard ancestor, and Nevin from Cork.
The Kavanagh branch from Skerries in North Co. Dublin back to the last 1700s, which includes Clarke, Monk/Moncks, Rooney, May & Hughes
and finally the imports! - Wilson from Yorkshire (originally Cambridgeshire and possibly Lincolnshire.. ) and the rest Shepherd, Bickerdike, Hayes etc.. form Yorkshire. Apparently the Hayes family, who were based in Sherburn-in-Elmet, had some connection back to Ireland - possibly Co. Galway.
Shane