A friend’s thoughtful meditation on the different natures of Irishness and Jewishness:

Irishness, at least in its North London manifestation, was clearly a much more inclusive category than I had been prepared for.  There were quite a few Black Irish people, and one or two Chinese ones.  There were a couple of others with what looked to me like Jewish faces, though they might equally have been Greek.
I don’t know how everyone in the room felt about this; but I do know that there was no outward sign that anybody had any feelings about it at all. Then and subsequently, I have never come across any handwringing about who the traditional music activities ought to be for, let alone ‘who is an Irish person?’ The activity was Irish in content, and that was enough.  Other, non-Irish people’s participation did not detract from its Irishness or threaten its existence or value.
In our community, interest by others in our culture is rarely taken at face value.  Although discussions about Jewish culture are often shot through with barely-veiled assumptions about cultural superiority, we are usually suspicious about anyone else wanting to partake.  Perhaps it’s because we are afraid that it won’t stand up to much scrutiny from anyone without a sentimental attachment to it; or maybe we are worried that they are only showing an interest so that they can insinuate themselves into our superior institutions. Why else would non-Jews be trying to sneak into our schools?
Either way, there is an all-pervasive obsession with maintaining and policing a boundary, with determining who is and isn’t entitled to come in.  Look at the selection processes associated with admission to Jewish schools, or the application forms for joining a synagogue.  No-one at Meitheal Cheoil ever asked me for my parents’ marriage certificate.
I don’t want to imply that Irish culture is inherently inclusive and anti-racist.  I’m sure that someone else could find plenty of counter-examples, together with joyous examples of Jewish inclusiveness and syncretism.  But I don’t think that the Jewish obsession with boundaries and separation, which make up an enormous proportion of our law and our lore, are merely accidental add-ons to our culture either. In biblical and talmudic Judaism, the principle of distinction and separation, and the importance of keeping things from mixing, is always imbued with a moral and theological dimension.
We are forbidden to mix meat and milk; fish and meat on the same plate; wool and linen in the same garment; and forbidden to yoke two kinds of animals to the same plough.  God does not like it when we mix things, stuff, or ourselves.  It’s worth remembering this next time you get into one of those discussions about the essential ethical core of Judaism.