Here is an interesting passage from Steven Pinker’s The Blank Slate:
In any case, there is now ample evidence that intelligence is a stable property of an individual, that it can be linked to features in the brain (including overall size, amount of gray matter in the frontal lobes, speed of neural conduction, and metabolism of cerebral glucose), that it is partly heritable among individuals, and that it predicts some of the variation in life outcomes such as income and social status. (p.150 paperback)
Conceptually, we can separate the question “Is there a physical/biological/genetic basis to intelligence” from the question “What moral implications does that have for society?” Still, it seems clear to me that there are moral implications that arise from the diversity in human intelligence. They are, however, connected to tricky moral problems, like what it means to ‘deserve’ one’s level of success or failure.
Modern genetics will improve health and usher in “designer” children
It may also provoke an ethical storm
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Stephen Hsu of Michigan State University, one of Genomic Prediction’s founders, acknowledges the theoretical risk of this, but argues that serious pleiotropic effects are unlikely. “If you looked at a bunch of kids with iqs of, say, 160 or 170,” he says, “I doubt you’d find much seriously wrong with them. They’d just be a bunch of geeks.” Dr Hsu, who in 2014 predicted that reproductive technologies would soon be used to select for more intelligent offspring, estimates that an iq gain of between 10 and 15 points would be possible if couples were allowed to choose between ten embryos. He also thinks that further gains would probably accumulate if people selected in this way went on to select their own offspring on the basis of intelligence.