Yes, there are a number of contributing factors to why Jews were disproportionately over-represented amongst leftist revolutionaries. Most significant is that the socialist movement was the first significant movement to openly denounce and confront anti-semitism. While Marx was outspokenly critical of Jewish culture, and Bakunin was a straightforward anti-semite, the ideologies of equality still found great appeal amongst the widely oppressed jewish peoples of Europe. It was in leftist movements that jewish leaders first truly began to take roles of leadership outside their own communities. People like Emma Goldman, Leon Trotsky, Rosa Luxembourg, and even Marx himself, demonstrated that jews could have a place in wider political movements. The rampant anti-semitism of conservative Europe also helped to ensure that the only viable political options for many jews was Zionism, socialism, or a combination of the two. Socialist and zionist political movements became the primary vehicles for organizing resistance to pogroms and anti-Semitic gangs such as the Black Hundreds and eventually the brownshirts. At a time when anti-Semitism was rarely denounced and few governments took any efforts towards addressing it, socialists took a firm stance on not just denouncing anti-semitism but in actively opposing it. Communists weren't the first to address anti-Semitism, but they did so in an era where it was still very significant.

Another large contributing factor in Eastern Europe was the success of the Jewish Bund. While Russian leftists generally were finding little success in winning over the common people they were claiming to represent, the Jewish Bund took an approach that focused on simple-to-understand pamphlets and community outreach. This paid off hugely and the Jewish Bund found success in spreading socialism amongst jewish laborers far before similar efforts began to work amongst the general Russian populace. This head start meant that by the time of the Russian revolution the Jewish community had already been widely exposed to socialist ideologies. Lenin and other organizers drew direct inspiration from the tactics of the Jewish Bund.

There is also discussion of how cultural values might have geared Jews towards socialism, but it can be hard to pin down just how much of a factor this was. The valuing of openness and the embrace of academia and criticism in Jewish culture may have contributed to some jews being more open to exploring socialism. In my opinion though it was oppression that was the greatest motivating factor, not any cultural proclivity. Similar phenomenons can be observed in the politics of other minority groups around the world.

Ultimately by the time socialist revolutions started coming to the forefront, these factors had combined to make jews disproportionately active in leftist movements, especially in both the Russian Empire and Germany. The antisemitism of Stalin's regime certainly put a damper on this connection, the prominence of zionism with the growth of Israel contributed to a growing rift within the Jewish community, and the holocaust also left many jews less comfortable with non-Jewish movements, but many still hold dear egalitarian values to at least some extent. This is pretty clearly demonstrated by the progressive voting habits of Jewish Americans, and the widespread continued presence of Jews in the civil rights movement.

I think it's a bit of a touchy topic, because the relationship between leftism and jews was the singular most prominent propaganda point of the Nazis. Many discussions on the topic can easily devolve into anti-semitic conspiracy and nazi talking points.

Aside from historical connections between Jewish communities and Communism (which do exist), it is important to note three contextual things about the specific atomic spies.

One is that Americans of Jewish descent for very obvious reasons were extremely anti-fascist, and for much of the 1930s the only group that consistently was uncompromising (except for the Molotov-Ribbentrop pact) against the Nazis were the Communists. From their perspective, everybody else waffled, thought they might be dealt with respectably, played at neutrality, did "both sides" rhetoric, and so on. This becomes self-reinforcing when this kind of thing was deliberately emphasized by the Communist Party and Comintern, as well.

The Molotov-Ribbentrop pact complicated this in general — it is why intelligence services made a big deal of people still being Communist Party members after the pact and before; it had a polarizing effect within the Communist movement abroad, and meant that anyone who stuck with them beyond that point were pretty much true Stalinists.

Second, the other major issue you've got in that demographic is that they're all from New York City, more or less. Some of them are from the same neighborhoods as one another. There are historical roots between certain areas of NYC and the labor movement, Communism, and so on, for that time period (and some beyond). And these happened to also be neighborhoods with high representation of Eastern European Jews.

Third, these names are not totally independently correlated; several of these people recruited from their friends and family. So for a small sample size you're going to see over-representation in such a case (Rosenberg–Greenglass–Sobell, and Hall–Sax, stand out in this respect — 1/3rd of the entire number).