Since Aug 2015 I have been working on a genealogy project for C123rd on Ancestry.com.
I have put the names of the 862 Marines and 161 Navy Corpsman who came and went in C Company during WWII into a tree at Ancestry.com.
If I could find their parents I added them and same for their spouses. About half of the men I could not find out more about. As I went along what struck me was how many were 1st generation Americans. 7 were even immigrants themselves of which 5 were born in Canada and 2 in Italy.
Of the ones whose parents I could find out more about, 120 of the Marines and Corpsmen were first generation Americans with their parents having been born in the following 33 countries.