My rosh yeshiva has said this yes that a large percent of these places are really Jewish. They are hidden Jews, so dont go crazy for Jewish candidates- there is a good shot we have already had a Jewish president and dont even know it.
There are geneologists who research these things and researching presidential candiates is always done. They found for example that Obama and Mitt Romney for example were 7th or 8th cousins. So there is definatly proof that there hasnt been a jewish president
I always hear people say, oh you know how many great Jews there are- like Einstein, Freud……Bernie Sanders. Who cares.
Jews like Einstein , freud, Salk, Sabin had great contributions to society and in some cases like Salk and Sabin saved millions of lives quantifiable. So if you dont care, then you dont care about Pikuach Nefesh. Einstein also likely saved lives too but its not as quantifiable as Salk/Sabin