Peter Goodfellow is a geneticist who tracked down the genetic essence of human ‘maleness’. In a high-profile scientific race to find the enigmatic ‘testis-determining factor’ (TDF; also known as sex-determining region Y (SRY) protein), Peter overturned others’ claims by correctly pinpointing the tiny SRY gene on the Y chromosome as the lynchpin of maleness in mammals.

Peter’s famous work began with his clever use of cell and molecular biology techniques to narrow down a segment of the Y chromosome as the location for the elusive TDF-encoding gene. Subsequently he found the crucial SRY gene and, with others, engineered a female mouse to become male through SRY expression.

In 1995, Peter won the Louis–Jeantet Prize for this work. The following year he began a decade-long chapter of his career, working in industry. Joining SmithKline Beecham as Head of Discovery, he then became — following a merger — Senior Vice-President of Discovery Research in the newly formed GlaxoSmithKline. Peter is now mostly retired.