How do immigrants forge a sense of identity?
Jews living outside Israel aren't the only people to ever have to wrestle with a double identity.
Immigrants all over the world, and their children, have faced the same personal dilemmas.
I speak from some experience. My Irish parents moved to Britain in the 1960s, when distrust between the neighbouring nations was still high.
Things are different now, but I still remember the look on my mother's face when I told her I had snubbed Dublin and applied for a British passport.
But of course Judaism is not just a cultural identity, it is also religious and, for some, a national ideal.
For the Jewish diaspora across the world, those elements have proved extremely durable.
Despite living in a variety of nations with different cultures and economic systems, over widely differing time periods, they have not only resisted being completely assimilated, they have successfully exported parts of their culture to the nation states which they call home.
What would Manhattan, for example, be without its Jews - and its bagels?
That is why the French prime minister said that modern-day France wouldn't be France without its Jews.
It wasn't always like that though.
The infamous Dreyfus Affair - where a Jewish officer in the French army who was wrongly convicted of treason was denied justice by a cover-up - was seen by many at the time as proof that Jews would never be fully trusted by their Christian countrymen.
Is this the situation that French Muslims now face?
If so, it is also one that English Catholics wrestled with in the past, when they were viewed with deep suspicion by the overwhelmingly Protestant establishment: who was their real allegiance to? Crown and country? Or the Pope in Rome, who demanded fidelity?
And in the modern day Islamic world, those perceived to be on the wrong side of the Shia/Sunni divide can also find themselves accused of disloyalty. Just look at Bahrain.
There is concern now, that the Jews, who are one of the most successfully integrated minority groups in countries like France, Britain and Belgium - may start to pack up and leave.
We know from experience that when communities do leave en masse - such as the Ugandan Asians expelled by Idi Amin in 1972 - the effects can be traumatic for all sides.
Of course, that kind of mass movement is not happening in France, but nonetheless emigration by French Jews to Israel rises each year.
There is talk of once-settled communities beginning to feel unsafe, perhaps unwanted, physically threatened and blamed for the ills of the Middle East. But there is another story as well.
Some of those Jews who swap the Eiffel Tower for the Western Wall make the return journey, after finding that Israel is not the promised land they expected.
And over the past week, French Jews have been declaring their loyalty to France, their insistence that this is home.
In Britain, a survey purporting to show that many Jews wanted to leave for Israel was swiftly followed by another, showing the exact opposite.
Ah, but why were those Jews who were shot dead in the Parisian siege last week buried in Jerusalem, and not Paris?
It seems that was a decision made by the victims' families.
Their loved ones were unlucky enough to be marked out by a killer because of their religious beliefs, so perhaps it is not surprising that at a moment of supreme trauma, those families would seek solace at the heart of their religion.
In truth, we can all hold multiple identities, some of them seemingly contradictory, yet still vital to our sense of self.
Just ask the patriotic Americans with Irish ancestors, many of whom have never set foot in the Emerald Isle but who call themselves Irish and turn a deep shade of green every St Patrick's Day.
That is a healthy contradiction that my mother would approve of.