Mendel’s green and yellow peas, he argued, were produced in ratios caused by ‘hidden determinants’. Their rediscovery at the beginning of the 20th century heralded the birth of genetics as a science.
During the 20th century these abstractions were first mapped on chromosomes (Morgan), and mutations dicovered (Muller), then understood as biochemically active (one gene one enzyme theory) and finally interpreted as sequences of DNA. The hidden determinants became visible as long strings of nucleotide bases (ACGT), and Crick formulated his ‘central dogma’ of the irreversible sequence by which DNA makes RNA makes protein. Only in the last twenty years has this dogma been challenged by the concept of the fluid genome, of DNA as but one actor in the economy of the cell.
Meantime, in the genetics clinic this immense technical and scientific change has transformed practice as the construction of risk is itself changed. Seeking to help families avoid giving birth to seriously genetically impaired babies had once turned on establishing family pedigrees and estimating probability. Now it is based on DNA testing, which, for some conditions (Huntington’s) offers not probability but certainty. The ethical and cultural problem is that this certainty is transferred to other DNA resuts (breast cancer) which only offer probability.
The second lecture is available here: The Biological Construction of Risk: From Mendel’s ‘Hidden Determinants’ to DNA Sequences - Lecture Two.

Professor Steven Rose is a Professor of Biology and Neurobiology at the Open University and University of London.
Rose read biochemsitry at King's College, Cambridge and neurobiology at Cambridge and the Institute of Psychiatry, King's College London. When he was appointed to the professorship of biology at the newly instituted Open University in 1969 he was Britain's youngest full professor and chair of department. At the Open University he established the Brain Research Group, within which he and his colleagues focussed on the biological processes involved in memory formation and treatments for Alzheimer's Disease on which he has published some 300 research papers and reviews.
He has written several popular science books and regularly writes for The Guardian. From 1999 to 2002, he was Professor of Physic at Gresham College with his wife Hilary Rose.
His work has won him numerous medals and prizes including the Biochemical Society medal for communication in science and the prestigious Edinburgh Medal. His book The Making of Memory won the Science Book Prize in 1993.

Hilary Rose has published extensively in the sociology of science from a feminist perspective and has held numerous appointments in the UK, USA, Australia, Austria, Norway, Finland and at the Swedish Collegium for the Advanced Study of the Social Science. In 1997 she was awarded an honorary doctorate by the University of Uppsala and in 2001 her book Love Power and Knowledge: Towards a feminist transformation of the sciences was listed one of the “101 Best Books of the 20th Century”. She collaborated for a number of years with the European Comission research division on mainstreaming women scientists in the European research system. She was the Gresham Professor of Physic with her husband Steven Rose between 1999 and 2002.