According to St. Jerome, Roman soldiers are the sons of what groups of people?

According to St. Jerome, Roman soldiers are the sons of Plebeians.

Explanation:

The plebeians were the common people of the time of the Romans. They were peasants and workers who worked on the land or did labor work or some other menial specialized work.

They were the ones fathering the future soldiers of Rome is what St Jerome, one of the prime early missionaries of Christianity opined.

The Christians understood that the Plebeians had been historically oppressed so focused on them a lot.

They were the prime converts to the faith in the beginning.