the Ancestry DNA looks at segments of DNA that show variation between major population groups - your DNA derives from both parents except that for males the Y chromosome derives entirely from the father - in each transfer down the generations there is a small chance of mutation which sequence of mutations is the key to traceing the MALE line - however I understand from your previous postings that your mother was a GI bride and derived from the Leicester area - this part of England was on the edge of the Danelaw region about a millennium ago - this area had many whose origins were in today's Denmark - to distinguish Manx ancestry you need to trace the male lines thus you need persuade one of your father's brothers or their male offspring to take a detailed DNA to distinguish between Irish and Manx Cain lines - your own DNA just confirms that your ancestors were probably a mix of Scandinavian (or N European) + Celtic (used as a shorthand for earlier native populations of the various parts of the British Isles) - a mix found in the vast majority of those deriving some or all ancestry in the British Isles.

Some years ago I did some work on the two Adam Caines found in mid 18th Century in the Kk Michael + Ballaugh region - these are on line at www.manxnotebook.com/famhist/families/index.htm there I give details of where I derived the information - if your own researches show up any errors I'd be very happy to correct these.