Notes from http://www.stirnet.com/HTML/genie/british/ff/fife1.htm#link3
Note:
In Gaelic, "mac in toisich" means 'son of the chief/leader". BLG1952 (Mackintosh of Mackintosh) reports this much-claimed connection, identifying Shaw as "2nd son of Duncan McDuff , the 2nd of that name, and 3rd Earl of Fife." The numbering of the earls differs between sources, so that difference is not considered significant, but the dates indicate that, if he was of this family, he was probably son of the 1st Duncan rather than the 2nd. In Gaelic, "mac in toisich" means 'son of the chief/leader".