But isn't "mental illness" genetic?
Don't we know from the genetic studies that "schizophrenia" is heritable?
Doesn't that mean it has to be a "biological" brain disease?
Amazingly, the answer again is no.
Yes, there is some heritability of schizophrenic symptoms. Identical twins whose twin exhibits schizophrenic symptoms are more likely to exhibit such symptoms themselves.
Amazingly, the answer again is no.
Yes, there is some heritability of schizophrenic symptoms. Identical twins whose twin exhibits schizophrenic symptoms are more likely to exhibit such symptoms themselves.
But the heritability of 50% that they routinely teach in Abnormal Psychology classes turns out to be as mythological as the chemical imbalances.
Virtually all human traits—e.g., neatness, shyness, criminal activity, conservative vs liberal values, overeating, athleticism, talkativeness, extroversion, religiosity, etc., etc.—show more similarity in pairs of identical twins, even if they are not raised together. The truth is that when the empirical data is examined, there is no evidence that schizophrenic symptom patterns are any more heritable than any other measurable human trait!
Indeed, the fact is that the low concordance rates actually found suggest the opposite: Since identical twins share the same genetic biology and since most identical twin pairs with one "schizophrenic" twin are not concordant for schizophrenia, it appears that biology cannot be more than just one piece of the story.
Virtually all human traits—e.g., neatness, shyness, criminal activity, conservative vs liberal values, overeating, athleticism, talkativeness, extroversion, religiosity, etc., etc.—show more similarity in pairs of identical twins, even if they are not raised together. The truth is that when the empirical data is examined, there is no evidence that schizophrenic symptom patterns are any more heritable than any other measurable human trait!
Indeed, the fact is that the low concordance rates actually found suggest the opposite: Since identical twins share the same genetic biology and since most identical twin pairs with one "schizophrenic" twin are not concordant for schizophrenia, it appears that biology cannot be more than just one piece of the story.
And this piece obviously cannot be the explanation: Again, most twins who have a schizophrenic identical twin are not concordant for schizophrenia. This lack of any indication that genetic, inborn biology accounts for the appearance of schizophrenic symptoms more than it accounts for any other human trait means that biology has to be a relatively minor part of the story, i.e., genetic biology explains no more about "schizophrenia" than it explains all other human behavior.
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