John Watson's famous 'dozen healthy infants' boast is usually quoted without its confession
The behaviourist John B. Watson is remembered for promising that, given a dozen healthy babies, he could train any of them into a doctor, lawyer or thief. The usual quotation stops there. The sentence that follows admits he was going beyond his facts, adding that the other side had been doing the same for thousands of years.
The modern phrase nature versus nurture was popularised by Francis Galton, Charles Darwin's half-cousin and the founder of both eugenics and behavioural genetics, though pairing the two ideas is ancient. In 209 BC the rebel Chen Sheng asked whether kings, generals and ministers were simply born to their station, a question later cited as an early take on the problem. John Locke's 1690 Essay argued that the mind starts as a blank slate, attacking Descartes's claim that everyone is born with an idea of God; the Earl of Shaftesbury retorted that Locke had thrown all order and virtue out of the world.
The pendulum kept swinging. The 19th century emphasised instinct, William James even arguing that humans have more instincts than animals. In reaction to Darwin's triumph, the early 20th century turned to environment: Franz Boas's 1911 work shaped American anthropology, Watson's behaviourism dominated for decades, and Ashley Montagu declared humans entirely without instincts apart from infants' startle reactions. Pushback grew in the 1970s with E. O. Wilson, while critics such as Richard Lewontin argued from a Marxist position that genetic determinism served class interests.
Twin studies helped cool things down. By splitting variation in a trait into genetic and environmental parts, they typically found heritability around 40 to 50 percent, significant but hardly total. In the 1980s the anthropologist Donald Brown catalogued about 150 cultural universals, and by the late 1990s cheaper genetics had buried the extreme blank-slate position. Steven Pinker's The Blank Slate in 2002 brought that shift to a wide readership.
Most researchers now see the dichotomy as of limited use. Donald Hebb captured why by answering the question of which contributes more to personality with another: which contributes more to a rectangle's area, its length or its width? Heritability describes variation across a population, not how much of any one person's trait comes from genes.
Source: Nature versus nurture
