Complex sentence: There are or should be similar lists of Irish, Scots, Welsh, Manx, Jersey, and Guernsey writers, naturally with overlaps, as writers may have multiple affiliations (e. g. born in Belfast, brought up in London).
Split into simpler sentences: There are or should be similar lists of Irish, Scots, Welsh, Manx, Jersey, and Guernsey writers. Naturally there is overlap between the lists, as writers may have multiple affiliations (e. g. born in Belfast, brought up in London).