Complex sentence: His Irish Catholic family was wealthy (his maternal grandfather, Dominick F. Burns, founded the Park Street Trust Company); but, from his earliest days, Dunne recalled feeling like an outsider in the predominantly WASPish West Hartford.
Split into simpler sentences: His Irish Catholic family was wealthy; his maternal grandfather, Dominick F. Burns, founded the Park Street Trust Company. However, from his earliest days, Dunne recalled feeling like an outsider in the predominantly WASPish West Hartford.