Genetic and epigenetic differences exist within monozygote twin-pairs and might be especially important in the expression of autism. Assuming phenotypic differences between monozygotic twins are due to environmental influences may lead to mistaken conclusions regarding the relative genetic and environmental contribution to autism risk.

A recent large-scale meta-analysis of twin and adoption studies indicated that shared environmental influences make important contributions to most forms of child and adolescent psychopathology (Burt, 2009b). The sole exception to this robust pattern of results was observed for attention-deficit/hyperactivity disorder (ADHD), which appeared to be…

Comments on the article by E. Diener, R. E. Lucas, and C. N. Scollon (see record 2006-05893-003) which cited a study by Tellegen et al. in which the Well-Being scale of the Multidimensional Personality Questionnaire (MPQ), administered to 44 pairs of monozygotic reared-apart (MZA) twins, yielded a within-pair correlation of 0.48. I contend that,…

Reviews genetic influence on suicide. Reviews methodologies for studying the nature-nurture issue and examines their applicability to the study of suicide. Reviews research from the methodologically sound strategies. Examines work by Uematsu using an approach different from any of the conventional methodologies. (Author/ABB)

Presents interview with Thomas Bouchard, a leading researcher of identical twins reared apart. Describes major themes in the Minnesota twin research. Claims, although genetic influence is central, Bouchard pleas for the impact of environmental factors in optimal human development. Includes Bouchard's surprising experiences, current focus, and…

Comments on Joseph's review of the genetics of attention deficit disorder, demonstrating errors of scientific logic and oversight of relevant research in Joseph's argument. Argues for the validity of twin studies in supporting a genetic link for ADHD and for the complementary role of nature and nurture in the etiology of the disorder. (JPB)

Answers the most important criticisms by Faraone and Biederman in their critique of Joseph's analysis of evidence supporting a genetic basis of attention deficit hyperactivity disorder. Argues that possible genetic and environmental influences in ADHD twin studies are confounded, obscuring inferences about genetic factors. (JPB)

Notes two faulty aspects of the Reznick et al., twin study (PS 526 688): the expressive language measure at 14 months, which has practically no spread of item difficulty, as well as measures included to assess specific cognitive characteristics; and the notion of infant transition as it affects interpretation of the results. (HTH)

This interview conducted with adult twin sisters legally blind since birth focuses primarily on their experiences with residential education--their relationship with their family, positive and negative aspects of residential education, how the experiences shaped their adult life, and changes needed in residential schools. (JDD)

A research study of identical twins, by Thomas J. Bouchard Jr., discloses that genetics exert a stronger influence over personality than we thought. Parents and teachers are advised to be active and alert observers of children's interests and talents to provide appropriate tools and resources to develop these propensities. (MLF)

This commentary details a number of problems with the study design and data analysis reported by Finkel et al. The commentary also provides suggestions for more fruitful approaches for analyzing data from such studies in the future. (Author/BC)

"The Bell Curve" declares that studies of separated identical twins--the "purest" of "direct" methods for estimating IQ heritability--indicate a value of +.75-+.80. But, the main study cited suggests a heritability of "two-thirds" for the middle class, and Herrnstein and Murray neglect to mention numerous…

M. McGue, I. Elkins, B. Walden, and W. G. Iacono (see record 2005-14938-011) presented the findings from a twin study examining the relative contributions of genetic and environmental factors to the developmental trajectories of parent-adolescent relationships. From a behavioral genetics perspective, this study is well conceptualized, is well…

Describes the interdisciplinary research of Myrtle B. McGraw; examines the controversy about McGraw's concept of critical period; and assesses her impact on current research. McGraw contended that the overlapping phases involved in neuromuscular integration demonstrate that learning and maturation interact during development. (BC)

Examines the case of two five-year-old twin boys with delayed language development, yet judged to be articulate and successful students in kindergarten. Suggests that the delay appeared because most of their interaction had been with each other. However, through their family they became acquainted with the discourse activities that are valued at…