We have a rule here at Jew or Not Jew. No, we're not talking about "don't pick your nose if a co-worker is looking", although that's a good rule that should always be followed. We're talking about "goy, until proven Jewish".
You see, there are a lot of potential profiles out there whose family history is just not clear. Who are not on record about their ethnic origins or their religious beliefs. People who we just have to make our best possible guess on.
And for those people, we use the "goy, until proven Jewish" rule.
Take basketball coach Rick Adelman. "Adelman" sure sounds Jewish, doesn't it? But other than the last name, there is absolutely no other evidence. In fact, if you start digging through his ancestry, you meet some clearly goyishe, German Adelmans.
Could a Jew have slipped in there? Sure. But considering the way us Jews attempt to grab onto and publicize every professional athlete and coach with any traces of Jewish ties, and no such attempts have ever been made about Adelman, we highly doubt it. So "Not a Jew" it is.
Oh, he went to a Catholic high school AND university? Well, that settles it, doesn't it? Lest we forget "Jews can attend a Christian high school, or a Christian college, but never both" rule...