Embryo Project Encyclopedia Articles

In the article “The History of Twins, As a Criterion of the Relative Powers of Nature and Nurture,” Francis Galton describes his study of twins. Published in 1875 in Fraser’s Magazine in London, England, the article lays out Galton’s use of twins to examine and distinguish between the characteristics people have at birth and the characteristics they receive from the circumstances of life and experience. Galton calls those factors nature and nurture. Based on his study, Galton concluded that nature has a larger effect than nurture on development. By studying twins, Galton introduced a way to examine the effects of nature and nurture in people who were born with similar traits, which allowed him to focus on the effects of experience on a person’s development.

Norman Haire was a physician who advocated for eugenics, which is the betterment of human population by promoting positive traits, and birth control rights in the twentieth century in both Australia and the UK. In the UK, Haire joined the Malthusian League, a contraception advocacy organization, and helped the League open the first physician-supervised birth control clinic, called Walworth Women’s Welfare Centre in London, England. Throughout his life, Haire worked closely with other well-known contraception and women’s rights advocates in the early 1900s including Margaret Sanger, Marie Stopes, and Havelock Ellis. Haire was also known for his work on sexual rejuvenation, an early twentieth century theory that the male sexual appetite could be restored through vasectomies and hormonal injections. Haire advocated for birth control rights through his practice, conference lectures, radio debates, and published work. His activism in the fields of eugenics, contraception, and sexual reform promoted the emergence of more liberal attitudes towards sex and controlled reproduction and in the twentieth century.

In 1990, Thomas J. Bouchard and his colleagues published the paper “Sources of Human Psychological Differences: The Minnesota Study of Twins Reared Apart” in Science Magazine. The paper described the results of a study initiated in 1979 on the development of twins raised in different environments. The scientists conducted their experiment at the University of Minnesota, in Minneapolis, Minnesota. The researchers physiologically and psychologically assessed monozygotic twins or triplets who were reared apart, comparing the similarity of those twins to twins who were reared together. The research team found that identical twins who are reared apart had the same chance of being similar as twins who were raised together. Bouchard and his colleagues concluded that genetic factors have a large influence on behavioral habits demonstrating the influence of the genetics on development.

The Malthusian League, founded in London, England, in 1877 promoted the use of contraception to limit family size. Activists Charles Bradlaugh and Annie Besant established the Malthusian League after they were arrested and exonerated for publishing a pamphlet describing techniques to prevent pregnancy. Founders based the league on the principles of Thomas Malthus, a British nineteenth century economist, who wrote on the perils of a population growing beyond the resources available to support it. The Malthusian League advocated for limiting family size voluntarily through contraception to avoid the overpopulation and poverty cautioned in Malthus’ work. After fifty years, the Malthusian League closed due to the increasing disapproval for Malthus’s economic theories of population and poverty. However, the Malthusian League’s activism during the late nineteenth and early twentieth centuries led to more tolerant views of contraception and family planning in Great Britain in the twentieth century.