Wednesday, June 29, 2016

Behavioral Genetics:

Why We're Different
Robert Plomin [6.29.16]

What we're trying to do in behavioral genetics and medical genetics is explain differences. It's important to know that we all share approximately 99 percent of our DNA sequence. If we sequence, as we can now readily do, all of our 3 billion base pairs of DNA, we will be the same at over 99 percent of all those bases. That's what makes us similar to each other. It makes us similar to chimps and most mammals. We're over 90 percent similar to all mammals. There's a lot of genetic similarity that's important from an evolutionary perspective, but it can't explain why we're different. That's what we're up to, trying to explain why some children are reading disabled, or some people become schizophrenic, or why some people suffer from alcoholism, et cetera. We're always talking about differences. The only genetics that makes a difference is that 1 percent of the 3 billion base pairs. But that is over 10 million base pairs of DNA. We're looking at these differences and asking to what extent they cause the differences that we observe. 
ROBERT PLOMIN is a professor of behavioral genetics at King's College London and deputy director of the Social, Genetic and Developmental Psychiatry Centre at the Institute of Psychiatry, Psychology and Neuroscience.
See the rest of the article here: https://www.edge.org/conversation/robert_plomin-why-were-different
If you look at the books and the training that teachers get, genetics doesn't get a look-in. Yet if you ask teachers, as I've done, about why they think children are so different in their ability to learn to read, and they know that genetics is important. When it comes to governments and educational policymakers, the knee-jerk reaction is that if kids aren't doing well, you blame the teachers and the schools; if that doesn't work, you blame the parents; if that doesn't work, you blame the kids because they're just not trying hard enough. An important message for genetics is that you've got to recognize that children are different in their ability to learn. We need to respect those differences because they're genetic. Not that we can’t do anything about it.

Tuesday, June 28, 2016

Why it is useful to understand the role of genetics in behaviour


Scientists have studied twins for many years to understand how genes and environments influence differences among individuals, spanning conditions such as cancer and mental health to characteristics such as intelligence and political beliefs.
Although the twin method is well-established, findings from twin studies are often controversial. Critics of twin research question the value of establishing that characteristics, such as health behaviours, have a strong genetic basis. A primary concern is that these types of findings will result in complacency or fatalism, effectively undermining motivation to change lifestyle. But there is very little evidence to support these fears.
Genetic influence on human characteristics is often misinterpreted. It is wrongly assumed that a behaviour that has strong genetic influence (highly heritable) must be biologically hardwired. However, genes are not destiny. Genes are often dependent on environmental exposure, such that genes can have a stronger effect, or no effect, depending on the environment.

Monday, June 27, 2016

Genetics and intelligence differences: five special findings


OPEN

R Plomin1 and I J Deary2,3
  1. 1King's College London, MRC Social, Genetic & Developmental Psychiatry Centre, Institute of Psychiatry, DeCrespigny Park, London, UK
  2. 2Department of Psychology, University of Edinburgh, Edinburgh, UK
  3. 3Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, Edinburgh, UK
Correspondence: Professor R Plomin, King's College London, MRC Social, Genetic & Developmental Psychiatry Centre, PO80, Institute of Psychiatry, DeCrespigny Park, Denmark Hill, London SE5 8AF, UK. E-mail: robert.plomin@kcl.ac.uk
Received 14 March 2014; Revised 18 July 2014; Accepted 22 July 2014
Advance online publication 16 September 2014
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Abstract

Intelligence is a core construct in differential psychology and behavioural genetics, and should be so in cognitive neuroscience. It is one of the best predictors of important life outcomes such as education, occupation, mental and physical health and illness, and mortality. Intelligence is one of the most heritable behavioural traits. Here, we highlight five genetic findings that are special to intelligence differences and that have important implications for its genetic architecture and for gene-hunting expeditions. (i) The heritability of intelligence increases from about 20% in infancy to perhaps 80% in later adulthood. (ii) Intelligence captures genetic effects on diverse cognitive and learning abilities, which correlate phenotypically about 0.30 on average but correlate genetically about 0.60 or higher. (iii) Assortative mating is greater for intelligence (spouse correlations ~0.40) than for other behavioural traits such as personality and psychopathology (~0.10) or physical traits such as height and weight (~0.20). Assortative mating pumps additive genetic variance into the population every generation, contributing to the high narrow heritability (additive genetic variance) of intelligence. (iv) Unlike psychiatric disorders, intelligence is normally distributed with a positive end of exceptional performance that is a model for ‘positive genetics’. (v) Intelligence is associated with education and social class and broadens the causal perspectives on how these three inter-correlated variables contribute to social mobility, and health, illness and mortality differences. These five findings arose primarily from twin studies. They are being confirmed by the first new quantitative genetic technique in a century—Genome-wide Complex Trait Analysis (GCTA)—which estimates genetic influence using genome-wide genotypes in large samples of unrelated individuals. Comparing GCTA results to the results of twin studies reveals important insights into the genetic architecture of intelligence that are relevant to attempts to narrow the ‘missing heritability’ gap.

Tuesday, June 07, 2016

Genetic test predicts your success in life, but not happiness

“It is important that people recognise and respect genetic scores,” says Plomin. “When kids don’t do well, we blame their teachers and parents, but kids vary genetically. [A low polygenic score] doesn’t mean a kid can’t learn, but we should recognise that it might take more effort.”


People with scorecards

What’s your genetic score?