Remeber that a correlation of .50 means that 25% of the variance is a
population is caused by the variable selected ( Variance = correlation
squared)
>From: Stephen Black <[EMAIL PROTECTED]>
>To: TIPS <[EMAIL PROTECTED]>
>Subject: Harris debate
>Date: Fri, 2 Feb 2001 13:35:07 -0500 (EST)
>
>On Thu, 1 Feb 2001 [EMAIL PROTECTED] wrote:
> >
> > I am wondering why a more middle-of-the-road view on this
> > question is not being studied (or is it, and I am just
> > clueless?)
> >
> > That is, it makes little sense to say, however convincingly,
> > that parents have virtually NO influence on how their
> > children turn out< snip>
>
>The problem with this otherwise reasonable point of view is that
>there is data on the question, and the data argue otherwise. For
>example, Bouchard et al (1990) report the correlation on a
>personality test (the MMPI) for identical twins reared apart as
>0.50, and for identical twins reared together as 0.49. For a test
>of religiosity, it's 0.49 for twins apart, and 0.51 for together;
>for social attitudes, it's 0.34 for apart, 0.28 for together. In
>other words, identical twins resemble each other in personality
>and social attitudes to the same extent whether brought up in the
>same family or different. Being brought up in the same family
>does have virtually NO influence. This is confirmed by data
>showing that the correlation on personality traits of two
>unrelated children brought up in the same family is 0.07, i.e.
>virtually none (Shaffer, 1999, p. 98, cites Loehlin, 1985 for
>this).
>
>Plomin (1994) also cites Loehlin (1992) for data showing that the
>shared environment effect of extraversion, neuroticism,
>agreeableness, conscientiousness, and openness to experience
>range from 0.10 to 0.10, while non-shared plus error values range
>from 0.43-0.49 on the same characteristics.
>
>These ideas are nicely summarized by Turkenheimer's (2000) Third
>Law:
>
>"A substantial portion of the variation in complex human
>behavioral traits is not accounted for by the effects of genes or
>families". And that leaves only non-shared environment to account
>for them, such as Harris's peer influences.
>
>Two qualifiers: the finding that there is virtually no influence
>of family environment on personality and social attitudes is
>often extented to IQ, but I think this is incorrect. The data do
>show that family environment contributes to IQ. For example
>Bouchard's (1990) figures show that the correlation for MZ twins
>together for IQ is 0.88, which drops to 0.69 for twins apart.
>Plomin (1994) gives the shared environment contribution to IQ as
>30%, which is more than his estimate for non-shared (10%).
>Adoption studies also indicate a moderate correlation between
>unrelated siblings reared together for IQ. So if you want to take
>credit for making your kids what they are, claim you made them
>smarter rather than more sociable.
>
>The other qualifier is that I agree with Harry Avis that the
>conclusions from twin studies are limited by the characteristics
>of the sample. It's possible that more extreme variation in
>upbringing than is represented in the twin studies might
>demonstrate a stronger influence of family environment. But until
>someone can show that, it remains unproven.
>
>-Stephen
>
>
>Bouchard, T., et al (1990). Sources of human psychological
> differences: the Minnesota study of twins reared apart.
> Science, 250, 223-
>
>Shaffer, D. (1999). Developmental Psychology (5th ed.)
>
>Plomin, R. (1994). The Emanuel Miller Memorial Lecture
> 1993. Genetic research and identification of environmental
> influences. Journal of child psychology and psychiatry, 35,
> 817-834.
>
>Turkenheimer, E. (2000). Three laws of behaviour genetics and
>what they mean. Current Directions in Psychological Science, 9,
> 160--
>
>
>------------------------------------------------------------------------
>Stephen Black, Ph.D. tel: (819) 822-9600 ext 2470
>Department of Psychology fax: (819) 822-9661
>Bishop's University e-mail: [EMAIL PROTECTED]
>Lennoxville, QC
>J1M 1Z7
>Canada Department web page at http://www.ubishops.ca/ccc/div/soc/psy
> Check out TIPS listserv for teachers of psychology at:
> http://www.frostburg.edu/dept/psyc/southerly/tips/
>------------------------------------------------------------------------
>
>
>
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