Genetic Epidemiology, Translational Neurogenomics, Psychiatric Genetics and Statistical Genetics Laboratories investigate the pattern of disease in families, particularly identical and non-identical twins, to assess the relative importance of genes and environment in a variety of important health problems.
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PMID
16238870
TITLE
The equal environments assumption of classical twin studies may not hold.
ABSTRACT
The classical twin method - comprising comparisons of monozygotic (MZ) and dizygotic (DZ) twins - in the domain of cognitive abilities and attainments has led to wide acceptance of results suggesting a large amount of additive genetic variance, with far-reaching implications both for the nature of future studies on the causes of cognitive variance and for intervention policies, as in education. However, this interpretation is only valid if the method observes a number of conditions, which have to hold. Here, we show that the most crucial of these, namely, the equal environments assumption (EEA), may not hold. Consequently, differences in twin correlations might be at least partly explained by treatment effects from parents, teachers, peers, and so on. In addition, well-known interactions at various levels confound the model of simple additive effects on which the classical twin method is predicated and results are interpreted. For example, at a socio-cognitive level, DZ twins may respond to treatments differently from MZ twins. This interaction may further explain MZ-DZ correlation differences. There is abundant evidence for such interactive effects in published twin data. We suggest that there is a need for a more thorough examination of these problems.
DATE PUBLISHED
2005 Sep
HISTORY
PUBSTATUS PUBSTATUSDATE
pubmed 2005/10/22 09:00
medline 2006/12/14 09:00
entrez 2005/10/22 09:00
AUTHORS
NAME COLLECTIVENAME LASTNAME FORENAME INITIALS AFFILIATION AFFILIATIONINFO
Richardson K Richardson Ken K The Open University, UK.
Norgate S Norgate Sarah S
INVESTIGATORS
JOURNAL
VOLUME: 75
ISSUE: Pt 3
TITLE: The British journal of educational psychology
ISOABBREVIATION: Br J Educ Psychol
YEAR: 2005
MONTH: Sep
DAY:
MEDLINEDATE:
SEASON:
CITEDMEDIUM: Print
ISSN: 0007-0998
ISSNTYPE: Print
MEDLINE JOURNAL
MEDLINETA: Br J Educ Psychol
COUNTRY: England
ISSNLINKING: 0007-0998
NLMUNIQUEID: 0370636
PUBLICATION TYPE
PUBLICATIONTYPE TEXT
Journal Article
Review
COMMENTS AND CORRECTIONS
GRANTS
GENERAL NOTE
KEYWORDS
MESH HEADINGS
DESCRIPTORNAME QUALIFIERNAME
Cognition
Environment
Humans
Psychiatry
Research Design
Twin Studies as Topic methods
Twins, Dizygotic genetics
Twins, Monozygotic genetics
United Kingdom genetics
SUPPLEMENTARY MESH
GENE SYMBOLS
CHEMICALS
OTHER ID's