Lionel Penrose

Penrose was educated at the Downs School, Colwall and the Quaker Leighton Park School, Reading, and later St John's College, Cambridge[8] On leaving school in 1916, he served, as a conscientious objector, with the Friends' Ambulance Unit/British Red Cross in France until the end of the First World War. He went on to study at St. John's College, Cambridge; he was a Cambridge Apostle.[8] At Cambridge, he gained a first class degree in moral sciences before leaving for Vienna for a year, to study at the psychological department at the University of Vienna.[8] In 1928, he qualified with the conjoint in 1928 at St Thomas' Hospital before qualifying for a Doctor of Medicine in 1930.[9]

Penrose undertook research into schizophrenia, designing tests of intelligence that were non-verbal in nature that are still in use. He was one of the earliest investigators of phenylketonuria in the 1930s.[8]

Penrose's "Colchester Survey", produced as the report in 1938, in collaboration with the MRC called the MRC special report: No.229, Clinical and genetic study of 1,280 cases of mental defect,[8] was the earliest serious attempt to study the genetics of mental retardation. He found that the relatives of patients with severe mental retardation were usually unaffected but some of them were affected with similar severity to the original patient, whereas the relatives of patients with mild mental retardation tended mostly to have mild or borderline disability. Penrose went on to identify and study many of the genetic and chromosomal causes of mental retardation (then called mental deficiency). This body of work culminated in the book, The Biology of Mental Defect (Sidgwick and Jackson, Ltd., London, UK, 1949).

Penrose was a central figure in British medical genetics following World War II. From 1945 to 1965, he worked as Galton Professor at the Galton Laboratory at University College London. The first title of his chair was "Professor of Eugenics" (1945–1963), then he had it changed to "Professor of Human Heredity" (1963–1965). According to his successor, Professor Harry Harris, Penrose “never liked the name 'eugenics’, because it seemed to him to be too much associated with uninformed and dangerous policies of racial purification." Harris also reported the "long delay" in changing this name was due to "legal problems" associated with the original donation from Francis Galton and described how Penrose simply ignored the "eugenics" element of his job title.[9]

Penrose received a number of awards and honours including the 1960 Albert Lasker Award for Basic Medical Research.[6] The Lasker citation read:

"Professor Penrose and his associates have been responsible over the years for studies which touch all aspects of human genetics, include genetic analyses of most of the known hereditary diseases, contributions to mathematical genetics, biochemical genetics, the study of gene linkage in man, and theoretical work on the mutagenic effect of ionizing radiations. Most recently their attention has been turned to abnormalities of human chromosomes associated with congenital defects, particularly mongolism [Down syndrome]."[6]

Penrose's Law[4][5] states that the population size of prisons and psychiatric hospitals are inversely related, although this is generally viewed as something of an oversimplification.[10]

Penrose, a member of the Society of Friends (Quakers), was a lead figure in the Medical Association for the Prevention of War in the 1950s.

Penrose developed the Penrose method, a method for apportioning seats in a global assembly based on the square root of each nation's population. Such a voting system is based on the voting power of any voter (measured by the Penrose–Banzhaf index) decreasing with the size of the voting body as one over its square root. See also Penrose square root law.

Penrose was particularly interested in different facets of biology, for example fingerprint, demography, and cytogenetics, which were a result of his research into the problems of mental defect, especially Down syndrome. He did intensive research on the latter, communicating the results of his investigations in 1963 and winning the Joseph P. Kennedy Jr. Foundation Award for his contributions to the understanding of the causes of mental retardation.[8]

Penrose married Margaret Leathes in 1928 and they had four children:

• Oliver Penrose, born 1929, physicist;
• Sir Roger Penrose, born 1931, mathematical physicist and mathematician (with whom Lionel co-authored papers on the Penrose triangle); and who shared the 2020 Nobel Prize in Physics;
• Jonathan Penrose, born 1933, chess grandmaster and psychologist;
• Shirley Hodgson, born 1945, geneticist.

After Penrose's death, Margaret married the mathematician Max Newman (1897–1984). She died in 1989.

Penrose' father was James Doyle Penrose. His mother was Elisabeth Josephine Penrose (née Peckover) and his brother was Sir Roland Penrose, both British artists.[11][12]