Very true. Pop music in the ‘50s (before rock-n-roll) was dominated by Italian-Americans. Even operatic voices such as Mario Lanza and Ezio Pinza were popular. Part of it was immigration. Part of it was American GIs returning from WW2 Italy.
Re your post #6, is this true or false: Italian-American male singers had a built-in advantage because they had a larger-than-average chest cavity (with lungs to match) that enabled them to sing with greater ability.
Also, they came from a culture that promoted singing.