Academic journal article The Journal of Social, Political, and Economic Studies

Stranger in the Nest: Do Parents Really Shape Their Child's Personality, Intelligence, or Character

Academic journal article The Journal of Social, Political, and Economic Studies

Stranger in the Nest: Do Parents Really Shape Their Child's Personality, Intelligence, or Character

Article excerpt

Stranger in the Nest: Do Parents Really Shape their Child's Personality, Intelligence, or Character

David B. Cohen

John Wiley and Sons, 1999

Where do children's (and adults) personality, intelligence and character come from? Many questions of social policy, such as the origins and cures for poverty, depend on this question. Other questions of anthropologists care about, such as how much can differences in cultural rearing patterns affect children's behavior (and hence their behavior when they become adults) depend on this. Thus, this is more than a book about parenting.

How often do parents, having tried to raise the perfect child, one that reflect their values and goals, find that they have a "Stranger in the Nest", a child that turns out not to be one that reflects their values (including those of their culture) and desires? This happen often, and explain the title of the new book by University of Texas psychologist, David B. Cohen. The basic message of the book is given by the sub-title "Do Parents Really Shape their Child's Personality, Intelligence, or Character", with the answer a resounding no. Instead the book emphasizes the role of genetic and pre-natal events in shaping intelligence and personality.

The book puts the emphasis on the good news for parents whose children have turned out other than as they would wish. It points out how diseases such as schizophrenia, manic-depression, and autism were once blamed on poor parenting, but now they are regarded as due to biological causes that parents can not be blamed for. The evidence for these conclusions comes from family studies, especially those of twins and adopted children.

In the other direction, the numerous cases where well-intentioned and good parents produce criminal offspring are described. If outstanding individuals produce poor offspring, and poor parents often produce excellent offspring, differences in parenting within the normal range are unlikely to have major effects on basic personality.

Cohen also points to the common observation that siblings, even same sex siblings, are radically different, both in personality and intelligence (sibling IQ differences average 12 points, which is 70% of the 18 point difference among children randomly selected from the same population). This is hard to explain by traditional social rearing theories, since parents usually raise their children in the same way. Yet it is easily explained by a genetic theory (perhaps supplemented by there being a random component in development, such as Miller 1997 has proposed).

Some of best-documented genetic effects are for intelligence. Behavior genetics makes it possible to partition the environmental influence into that due to being reared in the same family (referred to as shared variance) and that due to other causes. One of the most striking findings is that the familial influences are so weak. Identical twins raised apart correlate about .75, while those reared together correlate .85. This suggests the effect of being reared together given identical genes is only. 1, really quite small. As small as this is, studies of the IQ resemblance of unrelated children adopted into the same household show that they have essentially zero IQ resemblance. This suggests that the effect of being reared in the same family is essentially zero. Most of the environmental effects documented (and behavior genetic methods do prove that there are environmental effects) appear to be due to things that siblings within the same family do not share. (Rowe 1994 presents much evidence for this).

Supporting evidence for the role of genes is provided by many findings. Brain size correlates with IQ, ability tests done at 6 months (before most environmental influences have had a chance to exercise their effects) correlate with childhood IQ, adult 10 correlates with the biological relatives of adoptees, but not with that of the adoptive parents, and IQ correlates with reaction times. …

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