Nancy Segal's "Born Together--Reared
Apart" is a thorough history of the project and of the 137 pairs of
star-crossed twins who made it possible. Ms. Segal, a key member of the
Minnesota team, focuses on the many scientific publications that emerged
from the data. But along the way, readers meet leading twin researchers
and a whole lot of twins--including the "Jim twins," the "giggle twins"
(who both laughed almost nonstop) and, most incredibly, Oskar, raised as
a Nazi, and his identical brother, Jack, who was raised as a Jew.
Some findings go down easy: As most would expect, identical twins raised
apart have virtually identical heights as adults. Some findings seem
obvious after the fact: Genes, but not upbringing, have a pretty big
effect on personality traits like ambition, optimism, aggression and
traditionalism. Other findings perennially cause outrage: The IQs of
separated identical twins are almost as similar as their heights.
Critics of intelligence research often hail the importance of practice
rather than inborn talent, but a three-day test of the Minnesota twins'
motor skills showed that how much you benefit from practice is itself
partly an inborn talent.
The Minnesota study's IQ results hit a nerve years before their
publication in 1990, overshadowing other controversies that might have
been. Many of its findings are bipartisan shockers. Take religion, which
almost everyone attributes to "socialization." Separated-twin data show
that religiosity has a strong genetic component, especially in the long
run: "Parents had less influence than they thought over their
children's religious activities and interests as they approached
adolescence and adulthood."
What about the funding?
The biggest funder was the Pioneer Fund, which was founded in 1937 by
eugenicist Wycliffe Draper, though the Department of Health and Human
Services was a close second. In the interest of transparency, Ms. Segal
discloses the source of every dollar. She freely admits that some
researchers were skittish about Pioneer, because of the foundation's
perceived "racial agenda." But pragmatism prevailed: "The Pioneer Fund
imposed no restriction on the investigators' procedures or
publications," she writes, adding: "As Bouchard [the study's director]
said in 2009, 'If not for Pioneer we would have folded long ago.'"
What about the broader social implications?
Ms. Segal has little patience for those who fear the social consequences
of the Minnesota Study. The facts are on her side. Scientific support
for the effect of heredity on ability, character, and success has been
mounting for decades, but Western societies are more tolerant than ever,
and more inclined to treat their members as individuals. Hatemongers
have no need to appeal to heredity. Nazis used genetics to rationalize
genocide. Communist regimes rejected genetics as "bourgeois" and
murdered millions for their counterrevolutionary family backgrounds.
When a powerful movement wants to commit a heinous crime, it makes up a
Overall, a good book, but Segal's earlier Entwined Lives is more accessible, better-written, and deeper.