Education and early life
Brenner was born in the town of Germiston, Gauteng, South Africa. His parents, Lena (née Blecher) and Morris Brenner, were Jewish immigrants. His father, a cobbler, came to South Africa from Lithuania in 1910, and his mother from Riga, Latvia, in 1922. He has one sibling, a sister, Phyllis.
He was educated at Germiston High School and the University of the Witwatersrand. Having joined university at the age of 15, it was noted during his second year that he would be too young to qualify for the practice of medicine at the conclusion of his six-year medical course, and he was therefore allowed to complete a Bachelor of Science degree in Anatomy and Physiology. He stayed on for two more years doing an Honours degree and then an MSc degree, supporting himself by working part-time as a laboratory technician. During this time he was taught by Joel Mandelstam, Raymond Dart and Robert Broom. His master thesis was in the field of cytogenetics. In 1951 he received the MBBCh degree.
Brenner received an 1851 Exhibition Scholarship from the Royal Commission for the Exhibition of 1851 which enabled him to complete a Doctor of Philosophy (DPhil) degree at the University of Oxford as a postgraduate student of Exeter College, Oxford supervised by Cyril Hinshelwood.