What has Murray found on IQ since The Bell Curve?
I’m aware of two further studies Murray did on the NLSY database: • an ingenious study of pairs of American siblings raised together in non-poor homes. Murray described his findings in the Sunday Times of London in 1997: “Each pair consists of one sibling with an IQ in the normal range of 90-110, a range that includes 50% of the population. I will call this group the normals. The second sibling in each pair had an IQ either higher than 110, putting him in the top quartile of intelligence (the brights) or lower than 90, putting him in the bottom quartile (the dulls). These constraints produced a sample of 710 pairs. How much difference did IQ make? Earned income is a good place to begin. In 1993, when we took our most recent look at them, members of the sample were aged 28-36. That year, the bright siblings earned almost double the average of the dull: 22,400 compared to 11,800. The normals were in the middle, averaging 16,800. [IQ Will Put You In Your Place, Charles Murray, Sunday Time
