Historically, the infantry ranks in the US military tend to come from the working class, not the wealthy. If MOH recipients disproportionately come more from forward deployed troops than the officer commissioned class, it makes sense that there’s a larger contingent of recipients who are immigrants or come from immigrant families.
Apologies for repeating myself but this directly addresses a question I posed in a sub-comment: of the total population, at the time, what proportion were considered working class?
The reason being, class distinction would only count if non-working classes were very statistically significant. Having never examined this before, I'm having a hard time getting solid information, and it appears superfically that the class distinctions of today may not quite apply.
I'm operating under the hypothesis that the vast majority of the population would have been considered "working class", probably with a variety of sub-strata within (think hobo who occassionaly works vs. prosperous sustenance farm who's a pillar of the community).
Was there an excess of places in officer school for middle class+, or did they have to compete for their place? If they couldn't break in, was it socially acceptable to choose not to fight with the troops?