Meijer Mug was the middle of three children of the deaf-mute couple Isaäc Mug and Esther Brilleman. He was born in Rotterdam on 11 August 1919 and had an older brother Abraham (1917) and a younger sister Mietje (1923).
His brother Abraham married Mietje Coster in March 1940, a daughter of Barend Coster and Betje van Coevorden. They lived in Doezastraat 29a in Rotterdam, where Abraham was arrested …