His theory of genetic assimilation probably has a Darwinian explanation, which contrast with the fact that Waddington himself was very critic about the notion of natural selection and Neo-Darwinism.

[5] In 1928, he was awarded an Arnold Gerstenberg Studentship in the University of Cambridge, whose purpose was to promote "the study of Moral Philosophy and Metaphysics among students of Natural Science, both men and women.

His friends included Gregory Bateson, Walter Gropius, C. P. Snow, Solly Zuckerman, Joseph Needham, and John Desmond Bernal.

[9] He would stay at Edinburgh for the rest of life with the exception of one year (1960–1961) when he was a Fellow on the faculty in the Center for Advanced Studies at Wesleyan University in Middletown, Connecticut.

Waddington, however, came to the view that the answers to embryology lay in genetics, and in 1935 went to Thomas Hunt Morgan's Drosophila laboratory in California, even though this was a time when most embryologists felt that genes were unimportant and just played a role in minor phenomena such as eye colour.

[a] In a period of great creativity at the end of the 1930s, he also discovered mutations that affected cell phenotypes and wrote his first textbook of "developmental epigenetics", a term that then meant the external manifestation of genetic activity.

The idea was based on experiment: Waddington found that one effect of mutation (which could modulate the epigenetic landscape) was to affect how cells differentiated.

After a few generations, the trait can be found in the population, without the application of heat, based on hidden genetic variation that Waddington asserted had been "assimilated".

The evolutionary biologists Theodosius Dobzhansky and Ernst Mayr both thought that Waddington was using genetic assimilation to support Lamarckian inheritance.

In particular, according to Wilkins, Waddington felt that the Neo-Darwinians badly neglected the phenomenon of extensive gene interactions and that the "randomness" of mutational effects, posited in the theory, was false.

[22] Even though Waddington became critical of the neo-darwinian synthetic theory of evolution, he still described himself as a Darwinian, and called for an extended evolutionary synthesis based on his research.

[22][23] Reviewing the debate in 2015, the systems biologist Denis Noble writes however that [Waddington] did not describe himself as a Lamarckian, but by revealing mechanisms of inheritance of acquired characteristics, I think he should be regarded as such.

He contributed to a book on the role of the sciences in times of war, and helped set up several professional bodies representing biology as a discipline.

His 1969 book Behind Appearance; a Study of the Relations Between Painting and the Natural Sciences in This Century (MIT press) not only has wonderful pictures but is still worth reading.