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Codebreakers: Makers of Modern Genetics

The Lionel Penrose papers

Lionel Penrose pioneered the genetic study of learning disabilities, and sought to distance the study of human genetics from its eugenic origins.

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Collection overview

Lionel Penrose (1898-1972) was a man of endless curiosity who combined his scientific interests with a delight in mathematical puzzles. He succeeded Karl Pearson and R A Fisher as Galton Professor of Eugenics at University College London, a post he held from 1945 until his retirement in 1965. However, he never liked the term 'eugenics': in 1954 he changed the title of the Galton Laboratory's journal from 'Annals of Eugenics' to 'Annals of Human Genetics', and in 1963 succeeded in renaming his chair the Galton Professorship in Human Genetics.  

Penrose continuous staircase
Continuous staircase, a sketch by Lionel Penrose, 1962
Credit: University College London

Penrose's collection is extensive, covering personal and family letters and papers, as well as a wealth of scientific correspondence, drafts and notes on his many and varied interests. He is best known for his work on issues that affect mental development in children: he studied the chromosomal disorder for which he coined the term 'Down's anomaly' (later changed to 'syndrome'). He made a particular study of finger, palm and footprints and their links to mental disorder. He wrote several important books on the genetics of learning disabilities, and his extensive scientific writings also covered the behaviour of crowds, crime, statistics, psychoanalysis and intelligence testing. He was a meticulous collector of data, and acted as a critical friend to his colleague J B S Haldane (whose papers in UCL have also been digitised).


Lionel Sharples Penrose combined a rigorously disciplined scientific and mathematical mind with a warm and generous heart that won him many friends among patients and colleagues alike.

He was born in London, the second of four sons in a Quaker family, many of whose members over several generations distinguished themselves in arts and sciences. On leaving school he served in the Friends' Ambulance Unit for the final two years of World War I, before going up to Cambridge to study mathematics and psychology. After studying psychoanalysis in Vienna, he returned to London and trained as a psychiatrist.

His work in mental hospitals led him to make the first detailed survey of patients with mental disabilities and their relatives, first published as 'Mental Defect' in 1933. His work on the genetics of mental impairment led to his appointment in 1945 as Galton Professor of Eugenics at University College London. He led his department's change of focus from eugenics to a broader enquiry into the genetics of disease.

During the 1930s he showed that older mothers were more likely to have babies with Down's syndrome. Later, the advent of technology that made it possible to see individual chromosomes enabled him and his colleagues to distinguish different genetic abnormalities within the syndrome. After his retirement, he founded the Kennedy-Galton Centre, a clinic and laboratory in the grounds of Harperbury Hospital, a large residential colony for people with learning disabilities in Hertfordshire, where he worked until his death.

Penrose was an ardent pacifist and wrote on the role of science in preventing war. He was an enthusiastic chess player and enjoyed devising intellectual puzzles. Two of his sons became professors of mathematics and another a British chess champion.

Originals held by... 

This material has been provided by UCL Special Collections where originals may be consulted. 

To eliminate the gene [for phenylketonuria]...would involve sterilising 1% of the normal population... Only a lunatic would advocate such a procedure to prevent the occurrence of a handful of harmless imbeciles.

Lionel Penrose, 'Lancet', 1946

Digitised book

The biology of mental defect

The biology of mental defect

by Lionel Penrose

In The Timeline

1933: Lionel Penrose discovers the role of maternal age in Down’s syndrome

Lionel Penrose discovers the role of maternal age in Down’s syndrome

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