looking for help with my great grand father. James Roderick MacKenzie

James Roderick MacKenzie was born on or about Dec 1, 1843 or 1844 in Pictou Nova Scotia. I received that information from his naturalization papers. I have been told by one uncle that James was adopted and one uncle says no he wasn't. I cannot find his marriage to Elllen Avery O'Connor about 1888 in Massachusetts, but I know she was his wife. on his death certificate ( Massachusetts, Sept 19,1918) she listed his parents as Alexander MacKenzie and Mary MacKenzie, both born in Nova Scotia. Any help would be useful.

thank you