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"BIG BRAIN", The Origins and Future of Human Intelligence, Gary Lynch and Richard Granger, 2008, pages 127 - 128
Nature and Nurture of the Brain
This could lead to downright disturbing interferences. Is it possible that we are born with genetic predispositions that affect the strength of connection tracts in our brains, and these in turn predetermine - predestine - our abilities for the rest of our lives?
The truth is quite different. Genetic predispositions are just that - tendencies that influence brain growth, not absolutes that dictate it. Indeed, it has routinely been found that the genetic features we are born with are likely to be responsible for about half of the differences between one individual and another - with the other half arising from genetic influences, which include environment, parenting, siblings, peers, school, and nutrition, to name but a few.
Comparative studies have been carried out of twins separated at birth, no-twins siblings (biological brothers and sisters), and adoptive siblings. Separated twins shared all genetic features but none their environmental influences; biological siblings share some of their genes and much of their environmental influences, and adoptive siblings share their environment but not genetic material.
Statistically, about half of the similarities among these groups can be accounted for their genetic backgrounds, and the remaining half cannot, and must be attributed to environment. Genetic predisposition is a tendency, but it not clearly a predestination. It is like that brain pathways are influenced in equal measures by nature and by nurture.
Again, the effect may be quite indirect. Studies in identical twins are often interpreted strictly in terms of genes and brains, but of course the twins share body types, hormone levels, visual acuity, an countless other variables, all of which affect the way the world treats them. How a child gets along in school is influenced by their height, weight, athleticism, skin color; and how the child get along will certainly influence his or her mental makeup. This is one reason that some scientists find claims of inheritance of cognitive skills and talents to be only weakly supported.
Moreover, brain pathways may underlie the entire diverse spectrum of individual abilities. These pathways, influenced by genes and environment, play apart in specifying differential abilities in music, in athletics, in affability - in a broad range of characteristic that make us who we are. Far from determining a linear ordering of individuals who will "win" or "lost," differential brain paths arrangements can grant a range of talents and gifts, leading in diverse directions, helping to generate populations of individuals each with unique trails to add to human mix.
The truth is quite different. Genetic predispositions are just that - tendencies that influence brain growth, not absolutes that dictate it. Indeed, it has routinely been found that the genetic features we are born with are likely to be responsible for about half of the differences between one individual and another - with the other half arising from genetic influences, which include environment, parenting, siblings, peers, school, and nutrition, to name but a few.
Comparative studies have been carried out of twins separated at birth, no-twins siblings (biological brothers and sisters), and adoptive siblings. Separated twins shared all genetic features but none their environmental influences; biological siblings share some of their genes and much of their environmental influences, and adoptive siblings share their environment but not genetic material.
Statistically, about half of the similarities among these groups can be accounted for their genetic backgrounds, and the remaining half cannot, and must be attributed to environment. Genetic predisposition is a tendency, but it not clearly a predestination. It is like that brain pathways are influenced in equal measures by nature and by nurture.
Again, the effect may be quite indirect. Studies in identical twins are often interpreted strictly in terms of genes and brains, but of course the twins share body types, hormone levels, visual acuity, an countless other variables, all of which affect the way the world treats them. How a child gets along in school is influenced by their height, weight, athleticism, skin color; and how the child get along will certainly influence his or her mental makeup. This is one reason that some scientists find claims of inheritance of cognitive skills and talents to be only weakly supported.
Moreover, brain pathways may underlie the entire diverse spectrum of individual abilities. These pathways, influenced by genes and environment, play apart in specifying differential abilities in music, in athletics, in affability - in a broad range of characteristic that make us who we are. Far from determining a linear ordering of individuals who will "win" or "lost," differential brain paths arrangements can grant a range of talents and gifts, leading in diverse directions, helping to generate populations of individuals each with unique trails to add to human mix.
"BIG BRAIN", The Origins and Future of Human Intelligence, Gary Lynch and Richard Granger, 2008, pages 127 - 128
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