Born in New York to 'prosperous Scotch-Irish parents' (Thomas MacDowell and Frances Knapp MacDowell), Edward Alexander MacDowell was said to be 'a direct descendant of an old Scotch-Irish Quaker family which came to America in the early eighteenth century'. This 1915 biography is more precise, stating that his grandfather, Alexander MacDowell, was born in Belfast; he emigrated to America in the early 1800s and there married an Ulsterwoman called Sarah Thompson. They were both Quakers.
MacDowell showed musical talent early in life and aged 16 his parents sent him to Paris for advanced study. Here is his Wikipedia entry. In 1896 Edward MacDowell and his wife Marian established the MacDowell Art Colony in New Hampshire, a centre for creative arts, which is still running today (website here). He died aged just 46.
Below is Julian Lloyd Webber playing one of MacDowell's most famous compositions - To A Wild Rose.