Sunday, November 25, 2018

What's My Destiny?

St. Augustine (d. 430) wrote extensively on predestination
For millennia philosophers and priests have tried to reconcile free will with the existence of an omnipotent, omniscient Deity. If God knows in advance that an individual will choose rightly or wrongly, then Judgment was foreordained and the individual really didn't have free will.

The predestination conundrum was a focus of intense debate because for most of human history the afterlife was more important than mortal existence, which was nasty, brutish, and short.

By the second half of the 20th century predestination became an intellectual exercise--interesting but hardly relevant. What mattered was this life. And the way to achieve the best outcome for each individual was to improve the environment in which one was reared. Better nutrition, medical care, education, and crime-free neighborhoods all became societal objectives and beneficiaries of government spending.

"Nurture" was the new orthodoxy. Human beings were malleable; given the right surroundings any man could be a caring nurse, and any woman could be a Marine. Johnny liking trucks and Susie liking dolls were mere social constructs that expressed society's artificial preferences, which could be reversed if children were trained differently. However, despite decades of effort to adjust and enrich environments, differences in life outcomes persisted. And Johnny continued to play with trucks and Susie with dolls.

The revolutions in DNA mapping, big data, and number-crunching have given rise to a new determinant of destiny: our fortunes are written in our genes. [bold added]
A century of research has found that these inherited DNA differences account for about 90% of the differences in people’s physical traits, such as height and eye color. What may come as a surprise is that DNA also accounts, on average, for about 50% of our differences in such psychological traits as personality, mental health and illness, and cognitive ability and disability.
Polygenic analysis: math required
But there's no single gene that is responsible for proficiency in the clarinet, there are dozens maybe even hundreds working in concert(!) that produce any trait or attribute. Only now do we have the technology to perform polygenic ("many gene") analysis. Number-crunching combinations of genes across thousands of individuals has enabled researchers to be much more accurate in their predictions:
This prediction of school performance is the most powerful polygenic score reported to date in the behavioral sciences. Predicting 15% of the differences in school performance might not seem like much, but it is a better predictor than the educational attainment of the students’ parents. My team showed that children with the 10% highest polygenic scores are five times more likely to go to university than children with the 10% lowest scores....

Polygenic scores for educational attainment not only predict performance in school but also success later in life, such as mate choice, occupational status, social mobility and even financial planning for retirement,
So, is free will dead? Scientists couch their findings in the language of probability:
It’s just a probabilistic prediction—genes are not destiny and heritability describes what is, not what could be—but it might still be hard to accept.
However, governments have been known to declare that "the science is settled" and proceed post-haste with policies and prohibitions based on probabilistic outcomes from studies that often can not be replicated.

Today an aspiring doctor may not get into the medical school of her choice. In the future her polygenic score may not even allow her to apply.

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