1996/07/01 by Alvin Pam, S.S. Kemker, Colin A. Ross +1 · 1 citation
Psychology · Medicine · Neuroscience · #Cognitive Abilities and Testing #Assisted Reproductive Technology and Twin Pregnancy #Autism Spectrum Disorder Research #Premise #Psychiatric genetics #Twin study #Genetics #Psychology #Behavioural genetics #Psychiatry #Biology #Philosophy #Heritability #Schizophrenia (object-oriented programming) #Epistemology
paper · pdf · doi:10.1017/s0001566000000945
openalex publication_date 1996/07/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/04
The comparison of MZ-DZ twins in behavioral genetics has produced what seems like irrefutable evidence for the heritability of many psychiatric disorders. But such research depends on the validity of the EEA--the "equal environments assumption"--as an underlying premise. In this paper, several empirical studies which support the EEA are critically reviewed in terms of methodology and the way data has been processed in a mathematical model called "path analysis". It turns out that studies investigating the EEA appear to be largely inadequate in terms of technique, as well as biased in the inferences drawn. Further, the "heritability" estimate--often taken to mean the influence of trait-specific genes--is merely a statistical abstraction derived from a matrix of correlations; this estimate encompasses many buried environmental effects so that "heritability" does not correspond to any underlying DNA structure. In conclusion, many MZ-DZ pedigree studies have dubious scientific value, given the non-viable premise of the EEA, as well as the misleading operational definition of what has been called "heritability".