"Double Trouble" by Mark A Jobling, BioMed Central, Investigative Genetics (27 June 2013) ssg: The misperception that a single gene (out of epigenetic context) can exert causality over a specific human trait is a persistent problem. It gets even worse when applied to behaviors, having been used to justify all sorts of spurious claims. Leicester, UK. “How unique are you?” — an infuriating question for anyone with a pedant’s ear for linguistic correctness, but one that’s posed many a time in the fervid world of public engagement in genetics. And the expected answer is ‘very’ - pedants notwithstanding. The conventional way to demonstrate this is to ask a series of questions about traits with a supposedly simple genetic basis: tongue-rolling, hitch-hiker’s thumb, direction of hair whorl, cleft chin, attached earlobes… Often a tiny square of innocent-looking paper is proffered, with instructions to place it on the tongue (rolling or otherwise); to some people it’s tasteless, while to others it’s bitter due to its content of phenylthiocarbamide, meriting a sugary antidote in the form of a Polo mint. Sometimes there’s a vase of freesias whose scent fills the air — at least, for those of us whose genes allow us to detect it. Less savoury aspects involve interrogations about the colour or the smell of a subject’s urine following the eating of beetroot or asparagus. Testing many such traits in a large group demonstrates that few people share the same combination, and emphasises how genetically different we all are. The problem is that, as John H. McDonald’s splendid Myths of Human Genetics website [udel.edu/~mcdonald/mythintro.html] illustrates, many of these traits are continuous rather than discrete, and most do not have a simple genetic basis at all. Tongue-rolling, for example, certainly has some genetic component, with children of tongue-rolling parents more likely to be rollers themselves, but is not a simple dominant phenotype, as is often assumed. Hitch-hiker’s thumb, cleft chin, and attached earlobes are assumed in the ‘human uniqueness’ tests to be binary characteristics, but in fact all show continuous variation. Click on the article title to read the complete text at Investigative Genetics and review the research paper (cf. below). "Double trouble." Mark A Jobling. Investigative Genetics 2013; 4(12). doi:10.1186/2041-2223-4-12 Note: This is an Open Access article distributed under the terms of the Creative Commons Attribution License (creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. #news #science #scienceeveryday #sciencesunday #technology #medicine #genetics #heritance #traits #uniqueness #concordance #nature #nurture #questionnaires #dissimilarity #monozygotic #twinregistry #dna #copynumber #forensics #research #abstract #download #infographic #audio #video #youtube #vimeo #sharongaughan
Posted on: Mon, 05 Aug 2013 12:41:42 +0000
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