That patrilineal DNA thing is useless when it comes to finding out a man's roots. The Y-chromosome study only tells you the genetic code of one particular remote male ancestor. Let's say that if you go back 15 generations (around 500 years) you have a Celtic great-great-great-great-great-great-great-great-great-great-great-great-great grandfather (who happens to be the guy from which you got your Y-chromosome). Guess what? You have 16,383 other great-great-great-great-great-great-great-great-great-great-great-great-great grandfathers and 16,384 great-great-great-great-great-great-great-great-great-great-great-great-great grandmothers. If over 30,000 of your 32,768 great-great-great-great-great-great-great-great-great-great-great-great-great grandparents were Jewish, not Celtic, then I think that you can safely state that you are of Jewish descent, not of Celtic descent.
BTW, the Celts were originally from Central Europe and spread first to France, Spain and Portugal and later to the British Isles. If you are Jewish, the likeliest explanation for having Celtic blood in you is due to the marriage of one of your Jewish ancestors in Central Europe or Spain with a man with Celtic blood.
I never SAID I was of Celtic descent...only that my Y-chromosome was pure Celt. And, if you knew your biology (as well as you know arithmetic) you would understand that the Y-chromosome does not get diluted over time in the patrilineal line as other non-sex chromosomes can. So, it is more equal than others.
Origins Of The British: (A Genetic Detective Story)
"Synopsis Unpublished mtDNA and Y-chromosome genetic data has rapidly piled up about the British people. Synthesising the new genetic evidence with linguistics, archaeology and history, Stephen Oppenheimer breaks dramatic findings about the origins of the British people. The first scoop is that the roots of English identity lie over 6000 years ago, not with the Anglo-Saxons. The 'Anglo-Saxon invasion' contributed only 5-10 per cent of male English genes. Instead, the genetic evidence reveals that the majority of English people derive directly from before the first farmers. Secondly, new genetic findings finally answer the question of Celtic genetic identity. The putative origins of the Celts is an issue real for millions of people, from sore-lunged Glasgow football fans to the refined Celtic diasporas of North America and Australia. Gene lines prove once and for all the continued existence of a discrete, British Atlantic coast-based population that first spread north from the Basque country at the end of the last Ice Age - not Iron Age Europe. The division between England and the Atlantic fringe started to build up from that time. Finally, Oppenheimer puts new detail on the genetic legacy of the Viking invasions. He reveals that Orkney and Shetland, far from being victims, had been part of the Scandinavian world long before the Viking onslaught and, through the evidence of their genes, participated actively in raids on Ireland and the colonization of Iceland. "
The Celts were also in Anatolia and so were bagpipes that the Ottomans inherited and played along with atabals during the assaults on Vienna to scare the Christians. To this day there are bagpipers in Turkey.
Or, maybe one or more of his very recent Celtic ancestors converted to Judaism.