Genes, Nature, Nurture and The Freedom of Self-Knowledge (HD)

twins studies: excludes abuse, self-reporting, pre-selected families

where a large %- anywhere from 20-70% of identical twins- do NOT share such alarming similarities

- the temperature surrounding turtle and crocodile eggs determined their gender

- young, yellow-skinned grasshoppers became permanently black skinned for camouflage if exposed to a blackened (burnt) environment at a certain age

- locusts living in a crowded environment developed vastly more musculature (suitable for migration) than locusts living in less crowded conditions

Eleanor Maguire discovered in 1999 when she and her colleagues conducted MRI scans on London cabbies and compared them with the brain scans of others.

In contrast with non-cabbies, experienced taxi drivers had a greatly enlarged posterior hippocampus—that part of the brain that specializes in recalling spatial representations.

On its own, that finding proved nothing; theoretically, people born with larger posterior hippocampi could have innately better spatial skills and therefore be more likely to become cabbies.

What made Maguire’s study so striking is that she then correlated the size of the posterior hippocampi directly with each driver’s experience: the longer the driving career, the larger the posterior hippocampus.

In 1932, psychologists Mandel Sherman and Cora B. Key discovered that IQ scores correlated inversely with a community’s degree of isolation: the higher the cultural isolation, the lower the scores. In the remote hollow of Colvin, Virginia, for example, where most adults were illiterate and access to newspapers, radio, and schools was severely limited, six-year-olds scored close to the national average in IQ. But as the Colvin kids got older, their IQ scores drifted lower and lower—falling further and further behind the national average due to inadequate schooling and acculturation. (The very same phenomenon was discovered among the so-called canal boat children in Britain and in other isolated cultural pockets). Their unavoidable conclusion was that “children develop only as the environment demands development.”

Using a late-twentieth-century average score of 100, the comparative score for the year 1900 was calculated to be about 60—leading to the truly absurd conclusion, acknowledged Flynn,

“that a majority of our ancestors were mentally retarded.”

Children in professionals’ homes were exposed to an average of more than fifteen hundred more spoken words per hour than children in welfare homes.

Over one year that amounted to a difference of nearly 8 million words which by age four, amounted to a total gap of 32 million words. They also found a substantial gap in tone and in the complexity of words being used.

In identical-twin comparisons, shared biology always grabs all the attention. Inevitably overlooked is the vast number of shared cultural traits: same age, same sex, same ethnicity, and, in most cases, a raft of other shared (or very similar) social ,economic, and cultural experiences.

in the first four years after birth, the average child from a professional family receives 560,000 more instances of encouraging feedback than discouraging feedback;

A working-class child receives merely 100,000 more encouragements than discouragements;

A welfare child receives 125,000 more discouragements than encouragements

in her 1981 book Identical Twins Reared Apart, Susan Farber reviewed 121 cases of twins described by researchers as “separated at birth” or “reared apart.” Only three of those pairs had actually been separated shortly after birth.

At the University of Minnesota, the average age of separated twins studied turned out to be forty, while their average years spent apart was thirty—leaving an average of ten years of contact prior to research interviews.

adhd studies, excludes abuse, self reporting

"know thyself"

parents have no effect on kids? arguing that is like determinism

even if true, kids have even less responsibility

myth of the soul - unharmed pure spirit