Morais was born in Livorno, Italy. He was the elder son and the third of nine children of Samuel and Bona Morais. The Morais family came originally from Portugal, being probably among the large number of Jews who fled thence from the Inquisition. At the time of Sabato's birth, Italy was in the thick of her great struggle for freedom. Samuel Morais was an ardent republican, at one time undergoing imprisonment for his political views, and his father, Sabato Morais, was prominently identified with the political movements of his day.