1. What common ancestry does England and
Ireland share?

Maybe this will help:  

A complete genetic map of Britain and Ireland, generated by scientists for the first time, provides proof of common ancestry going back hundreds of years.

The addition of a genetic map of Scotland by geneticists at the Royal College of Surgeons in Ireland and the University of Edinburgh completed the data.

The map identifies “genetic clusters” – common genetic characteristics in particular regions – using genomic analysis, and provides evidence of Ireland’s strong links to southwest Scotland and the Hebrides going back to the sixth century. All told, there are 43 distinct clusters identified across Britain and Ireland.

Explanation: