#34 Wikipedia is misleading people here.
If the person himself says in extremely clear words that he's not a Jew, he doesn't want to be called a Jew, is uncircumcised, and on top of that he doesn't look Jewish at all and his behaviour is also uncharacteristic - then probably media should not insist on calling him a Jew.
Fischer's nationality and citizenship were American - until he was totally mistreated, abused, robbed of all his memorabilia he had been collecting throughout his life, and as a result left the country for good - and so were his mother's (born in Switzerland though).
If Fischer was indeed exempt from playing on Saturdays (what's the source again, by the way?), it was due to his affiliation with the the Worldwide Church of God that started in the early sixties:
hwarmstrong.com/ar/Fischer.html Find in the page "on the sabbath you have to rest".