scholarly journals A Reevaluation of the 1990 “Minnesota Study of Twins Reared Apart” IQ Study

2022 ◽  
Author(s):  
Jay Joseph
Keyword(s):  
Cognitive Ability ◽  
Genetic Factors ◽  
Model Fitting ◽  
Monozygotic Twin ◽  
Cohort Effects ◽  
Genetic Influences ◽  
Control Group ◽  
Dizygotic Twin ◽  
Full Sample ◽  
Iq Scores

In 1990, Thomas J. Bouchard, Jr. and colleagues published the widely cited 1990 “Minnesota Study of Twins Reared Apart” (MISTRA) Science IQ study. To arrive at the conclusion that “IQ is strongly affected by genetic factors,” Bouchard and colleagues omitted their control group reared-apart dizygotic twin (“DZA”) IQ-score correlations. Near-full-sample correlations published after the study’s 2000 endpoint show that the reared-apart monozygotic twin (“MZA”) and DZA group IQ correlations did not differ at a statistically significant level, suggesting that the study failed the first step in determining that IQ scores are influenced by heredity. After bypassing the model-fitting technique they used in most non-IQ MISTRA studies, the researchers assumed that the MZA group IQ-score correlation alone “directly estimates heritability.” This method was based on unsupported assumptions by the researchers, and they largely overlooked the confounding influence of cohort effects. Bouchard and colleagues then decided to count most environmental influences they did recognize as genetic influences. I conclude that the MISTRA IQ study failed to discover genetic influences on IQ scores and cognitive ability across the studied population, and that the study should be evaluated in the context of psychology’s replication problem.

scholarly journals A Genetic Analysis of Coffee Consumption in a Sample of Dutch Twins

2009 ◽  
Vol 12 (2) ◽  
pp. 127-131 ◽  
Author(s):  
Jaqueline M. Vink ◽  
Annemieke S. Staphorsius ◽  
Dorret I. Boomsma
Keyword(s):  
Environmental Factors ◽  
Genetic Factors ◽  
Model Fitting ◽  
Coffee Consumption ◽  
Genetic Influences ◽  
Psychoactive Substance ◽  
Twin Registry ◽  
Genetic And Environmental Factors ◽  
Dutch Twins ◽  
Twin Resemblance

AbstractCaffeine is by far the most commonly used psychoactive substance. Caffeine is consumed regularly as an ingredient of coffee. Coffee consumption and coffee preference was explored in a sample of 4,495 twins (including 1,231 pairs) registered with the Netherlands Twin Registry. Twin resemblance was assessed by tetrachoric correlations and the influence of both genetic and environmental factors was explored with model fitting analysis in MX. Results showed moderate genetic influences (39%) on coffee consumption. The remaining variance was explained by shared environmental factors (21%) and unique environmental factors (40%). The variance in coffee preference (defined as the proportion of coffee consumption relative to the consumption of coffee and tea in total) was explained by genetic factors (62%) and unique environmental factors (38%).

Absolute Pitch Twin Study and Segregation Analysis

2011 ◽  
Vol 14 (2) ◽  
pp. 173-178 ◽  
Author(s):  
Elizabeth Theusch ◽  
Jane Gitschier
Keyword(s):  
Twin Study ◽  
Segregation Analysis ◽  
Genetic Factors ◽  
Large Population ◽  
Absolute Pitch ◽  
Monozygotic Twin ◽  
Segregation Ratio ◽  
Unknown Etiology ◽  
Dizygotic Twin ◽  
Using Data

Absolute pitch is a rare pitch-naming ability with unknown etiology. Some scientists maintain that its manifestation depends solely on environmental factors, while others suggest that genetic factors contribute to it. We sought to further investigate the hypothesis that genetic factors support the acquisition of absolute pitch and to better elucidate the inheritance pattern of this trait. To this end, we conducted a twin study and a segregation analysis using data collected from a large population of absolute pitch possessors. The casewise concordance rate of 14 monozygotic twin pairs, 78.6%, was significantly different from that of 31 dizygotic twin pairs, 45.2%, assuming single ascertainment (x2 = 5.57, 1 df, p = .018), supporting a role for genetics in the development of absolute pitch. Segregation analysis of 1463 families, assuming single ascertainment, produced a segregation ratio pD = .089 with SEpD = 0.006. Unlike an earlier segregation analysis on a small number of absolute pitch probands from musically educated families, our study indicates that absolute pitch is not inherited in a simple Mendelian fashion. Based on these data, absolute pitch is likely genetically heterogeneous, with environmental, epigenetic, and stochastic factors also perhaps contributing to its genesis. These findings are in agreement with the results of our recent linkage analysis.

Genetic Influences on Hallux Valgus in Koreans: The Healthy Twin Study

2014 ◽  
Vol 17 (2) ◽  
pp. 121-126 ◽  
Author(s):  
Chang-Hyung Lee ◽  
Sooji Lee ◽  
HyoJeong Kang ◽  
Da-Eun Jung ◽  
Yun-Mi Song ◽  
...  
Keyword(s):  
Hallux Valgus ◽  
Twin Study ◽  
Genetic Factors ◽  
Weight Bearing ◽  
Monozygotic Twin ◽  
Population Based ◽  
Genetic Influences ◽  
Relative Importance ◽  
Radiographic Assessment ◽  
Anterior Posterior

Hallux valgus (HV) is a common foot deformity of multifactorial etiology, but knowledge about the relative importance of genetics and environments on HV has been limited. In order to estimate genetic influences on HV, 1,265 adults, including 175 monozygotic twin (MZ) pairs, 31 dizygotic twin (DZ) pairs, and 853 first-degree singleton family members of the twins were included from the Healthy Twin study, a population-based twin-family cohort in Korea. All participants underwent foot examination and weight-bearing radiographic assessment (anterior-posterior and lateral) in addition to a general health survey. Of the subjects, 208 (16.4%) were classified as HV (as HV angle >20°). The genetic influence on HV was estimated to be substantial; the heritability of HV was 0.51 (95% CI 0.42–0.59) and the heritability of HV angle was 0.47 (0.38–0.56), while contributions from shared environmental effects were negligible. These findings suggest that genetic factors play an important role in determining HV deformity.

scholarly journals Intra- and Inter-population Variability in Mamelon Expression on Incisor Teeth

2018 ◽  
Vol 14 (3) ◽  
pp. 1-6
Author(s):  
Sassan Chegini-Farahini ◽  
Janet Fuss ◽  
Grant Townsend
Keyword(s):  
Ethnic Groups ◽  
Genetic Factors ◽  
Monozygotic Twin ◽  
Population Variability ◽  
Grade System ◽  
Indigenous Australians ◽  
Human Populations ◽  
Dizygotic Twin ◽  
European Descent ◽  
Dental Models

Although rounded protubernaces referred to as mamelons are observes commonly on the crowns of newly-emerged human incisor teeth, there have been very few systematic studies of their expression. The main aims of this study were to describe the nature and extent of variation of mamelon expression on permanent incisors within and between two different human populations, and to quantify the contributions of genetic and environmental influences to observed variability. Mamelon expression was scored according to a 12-grade system described by Fitzgerald et al (1983) using dental models of 104 indigenous Australians, as well as 287 singletons and 175 pairs of twins of European descent. Over 90% of all incisors displayed mamelons, akthough the pattern of expression differed significantly between maxillary and mandibular arches, tooth types and ethnic groups. There were no significant differences in expression between sexes of antimeric teeth. A three-mamelon form was most common on maxillary and mandibular central incisors in both ethnic groups, but different expressions were observed on lateral incisors. Percentage concordances for monozygotic twin pairs were higher generally than those for dizygotic twin pairs, indicating that genetic factors play a role in determining the mamelon expression. 

scholarly journals Conceptual and Data-based Investigation of Genetic Influences and Brain Asymmetry: A Twin Study of Multiple Structural Phenotypes

2014 ◽  
Vol 26 (5) ◽  
pp. 1100-1117 ◽  
Author(s):  
Lisa T. Eyler ◽  
Eero Vuoksimaa ◽  
Matthew S. Panizzon ◽  
Christine Fennema-Notestine ◽  
Michael C. Neale ◽  
...  
Keyword(s):  
Twin Study ◽  
Genetic Factors ◽  
Right Hemisphere ◽  
Genetic Correlations ◽  
Monozygotic Twin ◽  
Genetic Influences ◽  
Size Difference ◽  
Subcortical Structures ◽  
Structural Asymmetry ◽  
Left And Right

Right–left regional cerebral differences are a feature of the human brain linked to functional abilities, aging, and neurodevelopmental and mental disorders. The role of genetic factors in structural asymmetry has been incompletely studied. We analyzed data from 515 individuals (130 monozygotic twin pairs, 97 dizygotic pairs, and 61 unpaired twins) from the Vietnam Era Twin Study of Aging to answer three questions about genetic determinants of brain structural asymmetry: First, does the magnitude of heritability differ for homologous regions in each hemisphere? Despite adequate power to detect regional differences, heritability estimates were not significantly larger in one hemisphere versus the other, except left > right inferior lateral ventricle heritability. Second, do different genetic factors influence left and right hemisphere size in homologous regions? Interhemispheric genetic correlations were high and significant; in only two subcortical regions (pallidum and accumbens) did the estimate statistically differ from 1.0. Thus, there was little evidence for different genetic influences on left and right hemisphere regions. Third, to what extent do genetic factors influence variability in left–right size differences? There was no evidence that variation in asymmetry (i.e., the size difference) of left and right homologous regions was genetically determined, except in pallidum and accumbens. Our findings suggest that genetic factors do not play a significant role in determining individual variation in the degree of regional cortical size asymmetries measured with MRI, although they may do so for volume of some subcortical structures. Despite varying interpretations of existing data, we view the present results as consistent with previous findings.

scholarly journals Genes Determine Stability and the Environment Determines Change in Cognitive Ability During 35 Years of Adulthood

2009 ◽  
Vol 20 (9) ◽  
pp. 1146-1152 ◽  
Author(s):  
Michael J. Lyons ◽  
Timothy P. York ◽  
Carol E. Franz ◽  
Michael D. Grant ◽  
Lindon J. Eaves ◽  
...  
Keyword(s):  
Cognitive Ability ◽  
Young Adulthood ◽  
Genetic Factors ◽  
Middle Age ◽  
Early Adulthood ◽  
Armed Forces ◽  
Genetic Influences ◽  
General Cognitive Ability ◽  
Longitudinal Assessment ◽  
Factors Influencing

Previous research has demonstrated stability of cognitive ability and marked heritability during adulthood, but questions remain about the extent to which genetic factors account for this stability. We conducted a 35-year longitudinal assessment of general cognitive ability using the Armed Forces Qualification Test administered to 7,232 male twins in early adulthood and readministered to a subset of 1,237 twins during late middle age. The proportion of variance in cognitive functioning explained by genetic factors was .49 in young adulthood and .57 in late middle age. The correlation between the two administrations was .74 with a genetic correlation of 1.0, indicating that the same genetic influences operated at both times. Genetic factors were primarily responsible for stability, and nonshared environmental factors were primarily responsible for change. The genetic factors influencing cognition may change across other eras, but the same genetic influences are operating from early adulthood to late middle age.

Concordance for multiple sclerosis in Danish twins: an update of a nationwide study

2005 ◽  
Vol 11 (5) ◽  
pp. 504-510 ◽  
Author(s):  
T Hansen ◽  
A Skytthe ◽  
E Stenager ◽  
H C Petersen ◽  
H Brønnum-Hansen ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Genetic Factors ◽  
Monozygotic Twins ◽  
Monozygotic Twin ◽  
Population Based ◽  
Data Sets ◽  
Dizygotic Twin ◽  
Population Based Study ◽  
Nationwide Study ◽  
Dizygotic Twins

The occurrence of multiple sclerosis (MS) in twins has not previously been studied in complete nationwide data sets. The existence of almost complete MS and twin registries in Denmark ensures that essentially unbiased samples of MS cases among twins can be obtained. In this population-based study, virtually all Danish MS cases among twins born before 1983 with onset of MS after 1948 and diagnosis before 1 January 1997 were identified. Of 13 286 MS cases, 178 were twins and, of these 164 twin pairs were discordant and seven were concordant. We found significantly higher proband-wise concordance among monozygotic twins than dizygotic twins, with estimated proband-wise concordances of 24% (95% confidence interval (CI): 5-39%) for monozygotic and 3% (95% CI: 0-8%) for dizygotic twins. Thus, a monozygotic twin whose co-twin has MS has a 24% risk of developing the disease, while the corresponding risk for a dizygotic twin is only 3%. Our results largely confirm previously published concordance estimates and indicate that genetic factors are of importance in susceptibility to MS.

Clustering of insulin resistance, total and central abdominal fat: same genes or same environment?

Twin Research ◽  
1999 ◽  
Vol 2 (3) ◽  
pp. 218-225 ◽  
Author(s):  
Katherine Samaras ◽  
Tuan V Nguyen ◽  
Arthur B Jenkins ◽  
John A Eisman ◽  
Gabrielle M Howard ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Insulin Secretion ◽  
Environmental Factors ◽  
Genetic Factors ◽  
Intraclass Correlation ◽  
Model Fitting ◽  
Genetic Influences ◽  
Model Assessment ◽  
Central Fat ◽  
Total Fat

AbstractObesity, insulin resistance and disturbed glucose metabolism cluster within the Insulin Resistance Syndrome (IRS). Whether this reflects shared genetic or environmental factors detectable in ‘normal’ populations (not selected for IRS features) is unknown. This study estimated (i) genetic influences on IRS traits and (ii) shared and specific genetic and environmental factors on the relationships between these traits in healthy female twins. Fasting insulin, glucose, total and central fat were measured in 59 monozygotic (MZ) and 51 dizygotic (DZ) female twin pairs aged ( ± SD) 52 ± 13 years. Body fat was measured by dual-energy X-ray absorptiometry, insulin resistance and secretion by a modified homeostasis model assessment. Using intraclass correlation coefficients and univariate model-fitting analyses, genetic influences were found in total fat, central fat, insulin resistance, fasting glucose and insulin secretion, with genetic factors explaining 64, 57, 59, 75 and 68% of their variance, respectively, using the latter technique. In matched analysis intra-pair differences in total and central fat related to intra-pair differences in insulin resistance (r2 = 0.19, P < 0.001). Multivariate model-fitting showed a close genetic relationship between total and central fat (r = 0.88). The genetic correlation between IR and central fat (0.41) was significantly greater than that for total fat (0.24), suggesting that central fat is not only a predictor of, but shares considerable genetic influence with, insulin resistance. In Cholesky analysis, these genetic influences were separate from those shared between central and total fat. In conclusion, both shared and specific genetic factors regulate components of the IRS in healthy females. However, there were discrete genetic influences on -cell insulin secretion, not shared with other IRS components, suggesting that a separate genetic propensity exists for Type2 diabetes. These findings suggest we may understand the genetic and environmental influences on IRS from the study of the normal population.

Berat Badan, Panjang Badan dan Faktor Genetik sebagai Prediktor Terjadinya Stunted pada Anak Sekolah

2017 ◽  
Vol 19 (2) ◽  
pp. 95
Author(s):  
Hetriana Leksananingsih ◽  
Slamet Iskandar ◽  
Tri Siswati
Keyword(s):  
Birth Weight ◽  
Nutritional Status ◽  
School Children ◽  
Genetic Factors ◽  
Control Group ◽  
Case Group ◽  
Normal Birth Weight ◽  
Chi Square ◽  
Normal Birth ◽  
Chi Square Test

Background: Riskesdas in 2013 showed that Yogyakarta (DIY) had a prevalence of stunted new kid in school is less than the national average, which is 14.9% (MOH, 2013). Stunted or short, is a linear growth retardation has been widely used as an indicator to measure the nutritional status of individuals and community groups. Stunted can be influenced by several factors: birth weight, birth length match and genetic factors. Objective: To determine the weight, length of low birth weight and genetic factors as predictors of the occurrence of stunted on elementary school children. Methods: The study was a case control analytic. Research sites in SD Muhammadiyah Ngijon 1 Subdistrict Moyudan. The study was conducted in May and June 2015. The subjects were school children grade 1 to grade 5 the number of cases as many as 47 children and 94 control children. With the inclusion criteria of research subjects willing to become respondents, was present at the time of the study, they have a father and mother, and exclusion criteria have no data BB and PB birth, can not stand upright. The research variables are BBL, PBL, genetic factors and TB / U at this time. Data were analyzed by chi-square test and Odd Ratio (OR) calculation. Results: In case group as much as 91.5% of normal birth weight and length of 80.9% of normal birth weight, most of the height of a normal mother and father as many as 85.1%. In the control group as much as 78.7% of normal birth weight and 61.7% were born normal body length, height mostly normal mom and dad that 96.7% of women and 90.4% normal normal father. Statistical test result is no significant correlation between height mothers with stunted incidence in school children, and the results of chi-square test P = 0.026 with value Odd Ratio (OR) of 3.9 and a range of values from 1.091 to 14.214 Cl95%. Conclusion: High maternal body of mothers can be used as predictors of the occurrence of stunted school children and mothers with stunted nutritional status have 3.9 times the risk of having children with stunted nutritional status.

Cocaine use, abuse and dependence in a population-based sample of female twins

1998 ◽  
Vol 173 (4) ◽  
pp. 345-350 ◽  
Author(s):  
Kenneth S. Kendler ◽  
Carol A. Prescott
Keyword(s):  
Cocaine Abuse ◽  
Genetic Factors ◽  
Model Fitting ◽  
Population Based ◽  
Cocaine Use ◽  
Past Half Century ◽  
History Of ◽  
Population Based Registry ◽  
Twin Resemblance

BackgroundAlthough cocaine use in women has increased substantially over the past half-century, we understand little about the aetiology in women of cocaine use and abuse, and know almost nothing about the role of genetic factors.MethodWe obtained by telephone interview a history of lifetime cocaine use, abuse and dependence from 1934 individual twins from female–female pairs ascertained through a population-based registry, including both members of 485 monozygotic (MZ) and 335 dizygotic (DZ) pairs.ResultsThe prevalence of lifetime cocaine use, abuse and dependence were 14.0%, 3.3% and 2.3%. Probandwise concordance rates, in MZ and DZ twins, respectively, were: cocaine use 54% and 42%; cocaine abuse 47% and 8% and cocaine dependence 35% and 0%. In MZ and DZ twins, odds ratios were: cocaine use 14.2 and 6.7 and cocaine abuse 40.8 and 2.7. Biometrical model-fitting suggested that twin resemblance for liability to cocaine use was due to both genetic and familial–environmental factors while twin resemblance for cocaine abuse and symptoms of dependence was due solely to genetic factors. Estimated heritabilities were: cocaine use 0.39, cocaine abuse 0.79 and symptoms of dependence 0.65.ConclusionsThe vulnerability to cocaine use and particularly cocaine abuse and dependence in women is substantially influenced by genetic factors.

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