| 1. |
- Silventoinen, K., et al.
(författare)
-
The CODATwins Project : The current status and recent findings of COllaborative Project of Development of Anthropometrical Measures in Twins
- 2019
-
Ingår i: Twin Research and Human Genetics. - : Cambridge University Press. - 1832-4274 .- 1839-2628. ; 22:6, s. 800-808
-
Tidskriftsartikel (refereegranskat)abstract
- The COllaborative project of Development of Anthropometrical measures in Twins (CODATwins) project is a large international collaborative effort to analyze individual-level phenotype data from twins in multiple cohorts from different environments. The main objective is to study factors that modify genetic and environmental variation of height, body mass index (BMI, kg/m2) and size at birth, and additionally to address other research questions such as long-term consequences of birth size. The project started in 2013 and is open to all twin projects in the world having height and weight measures on twins with information on zygosity. Thus far, 54 twin projects from 24 countries have provided individual-level data. The CODATwins database includes 489,981 twin individuals (228,635 complete twin pairs). Since many twin cohorts have collected longitudinal data, there is a total of 1,049,785 height and weight observations. For many cohorts, we also have information on birth weight and length, own smoking behavior and own or parental education. We found that the heritability estimates of height and BMI systematically changed from infancy to old age. Remarkably, only minor differences in the heritability estimates were found across cultural-geographic regions, measurement time and birth cohort for height and BMI. In addition to genetic epidemiological studies, we looked at associations of height and BMI with education, birth weight and smoking status. Within-family analyses examined differences within same-sex and opposite-sex dizygotic twins in birth size and later development. The CODATwins project demonstrates the feasibility and value of international collaboration to address gene-by-exposure interactions that require large sample sizes and address the effects of different exposures across time, geographical regions and socioeconomic status.
|
|
| 2. |
|
|
| 3. |
- Silventoinen, K., et al.
(författare)
-
Educational attainment of same-sex and opposite-sex dizygotic twins : An individual-level pooled study of 19 twin cohorts
- 2021
-
Ingår i: Hormones and Behavior. - : Elsevier. - 0018-506X .- 1095-6867. ; 136
-
Tidskriftsartikel (refereegranskat)abstract
- Comparing twins from same- and opposite-sex pairs can provide information on potential sex differences in a variety of outcomes, including socioeconomic-related outcomes such as educational attainment. It has been suggested that this design can be applied to examine the putative role of intrauterine exposure to testosterone for educational attainment, but the evidence is still disputed. Thus, we established an international database of twin data from 11 countries with 88,290 individual dizygotic twins born over 100 years and tested for differences between twins from same- and opposite-sex dizygotic pairs in educational attainment. Effect sizes with 95% confidence intervals (CI) were estimated by linear regression models after adjusting for birth year and twin study cohort. In contrast to the hypothesis, no difference was found in women (β = −0.05 educational years, 95% CI −0.11, 0.02). However, men with a same-sex co-twin were slightly more educated than men having an opposite-sex co-twin (β = 0.14 educational years, 95% CI 0.07, 0.21). No consistent differences in effect sizes were found between individual twin study cohorts representing Europe, the USA, and Australia or over the cohorts born during the 20th century, during which period the sex differences in education reversed favoring women in the latest birth cohorts. Further, no interaction was found with maternal or paternal education. Our results contradict the hypothesis that there would be differences in the intrauterine testosterone levels between same-sex and opposite-sex female twins affecting education. Our findings in men may point to social dynamics within same-sex twin pairs that may benefit men in their educational careers.
|
|
| 4. |
- Jelenkovic, A, et al.
(författare)
-
Genetic and environmental influences on human height from infancy through adulthood at different levels of parental education
- 2020
-
Ingår i: Scientific reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 10:1, s. 7974-
-
Tidskriftsartikel (refereegranskat)abstract
- Genetic factors explain a major proportion of human height variation, but differences in mean stature have also been found between socio-economic categories suggesting a possible effect of environment. By utilizing a classical twin design which allows decomposing the variation of height into genetic and environmental components, we tested the hypothesis that environmental variation in height is greater in offspring of lower educated parents. Twin data from 29 cohorts including 65,978 complete twin pairs with information on height at ages 1 to 69 years and on parental education were pooled allowing the analyses at different ages and in three geographic-cultural regions (Europe, North America and Australia, and East Asia). Parental education mostly showed a positive association with offspring height, with significant associations in mid-childhood and from adolescence onwards. In variance decomposition modeling, the genetic and environmental variance components of height did not show a consistent relation to parental education. A random-effects meta-regression analysis of the aggregate-level data showed a trend towards greater shared environmental variation of height in low parental education families. In conclusion, in our very large dataset from twin cohorts around the globe, these results provide only weak evidence for the study hypothesis.
|
|
| 5. |
- Pedersen, N. L., et al.
(författare)
-
IGEMS: The Consortium on Interplay of Genes and Environment Across Multiple Studies
- 2013
-
Ingår i: Twin Research and Human Genetics. - : Cambridge University Press (CUP). - 1832-4274 .- 1839-2628. ; 16:1, s. 481-489
-
Tidskriftsartikel (refereegranskat)abstract
- The Interplay of Genes and Environment across Multiple Studies (IGEMS) group is a consortium of eight longitudinal twin studies established to explore the nature of social context effects and gene-environment interplay in late-life functioning. The resulting analysis of the combined data from over 17,500 participants aged 25–102 at baseline (including nearly 2,600 monogygotic and 4,300 dizygotic twin pairs and over 1,700 family members) aims to understand why early life adversity, and social factors such as isolation and loneliness, are associated with diverse outcomes including mortality, physical functioning (health, functional ability), and psychological functioning (well-being, cognition), particularly in later life.
|
|
| 6. |
- Silventoinen, Karri, et al.
(författare)
-
Education in twins and their parents across birth cohorts over 100 years : an individual-level pooled analysis of 42 twin cohorts
- 2017
-
Ingår i: Twin Research and Human Genetics. - Stockholm : Karolinska Institutet, Dept of Medical Epidemiology and Biostatistics. - 1832-4274 .- 1839-2628.
-
Tidskriftsartikel (refereegranskat)abstract
- Whether monozygotic (MZ) and dizygotic (DZ) twins differ from each other in a variety of phenotypes is important for genetic twin modeling and for inferences made from twin studies in general. We analyzed whether there were differences in individual, maternal and paternal education between MZ and DZ twins in a large pooled dataset. Information was gathered on individual education for 218,362 adult twins from 27 twin cohorts (53% females; 39% MZ twins), and on maternal and paternal education for 147,315 and 143,056 twins respectively, from 28 twin cohorts (52% females; 38% MZ twins). Together, we had information on individual or parental education from 42 twin cohorts representing 19 countries. The original education classifications were transformed to education years and analyzed using linear regression models. Overall, MZ males had 0.26 (95% CI [0.21, 0.31]) years and MZ females 0.17 (95% CI [0.12, 0.21]) years longer education than DZ twins. The zygosity difference became smaller in more recent birth cohorts for both males and females. Parental education was somewhat longer for fathers of DZ twins in cohorts born in 1990-1999 (0.16 years, 95% CI [0.08, 0.25]) and 2000 or later (0.11 years, 95% CI [0.00, 0.22]), compared with fathers of MZ twins. The results show that the years of both individual and parental education are largely similar in MZ and DZ twins. We suggest that the socio-economic differences between MZ and DZ twins are so small that inferences based upon genetic modeling of twin data are not affected.
|
|
| 7. |
- Hicks, B. M., et al.
(författare)
-
Gender differences and developmental change in externalizing disorders from late adolescence to early adulthood : A longitudinal twin study
- 2007
-
Ingår i: Journal of Abnormal Psychology. - Washington : American Psychological Association (APA). - 0021-843X .- 1939-1846. ; 116:3, s. 433-447
-
Tidskriftsartikel (refereegranskat)abstract
- Using data from over 1,000 male and female twins participating in the Minnesota Twin Family Study, the authors examined developmental change, gender differences, and genetic and environmental contributions to the symptom levels of four externalizing disorders (adult antisocial behavior, alcohol dependence, nicotine dependence, and drug dependence) from ages 17 to 24. Both men and women increased in symptoms for each externalizing disorder, with men increasing at a greater rate than women, such that a modest gender gap at age 17 widened to a large one at age 24. Additionally, a mean-level gender difference on a latent Externalizing factor could account for the mean-level gender differences for the individual disorders. Biometric analyses revealed increasing genetic variation and heritability for men but a trend toward decreasing genetic variation and increasing environmental effects for women. Results illustrate the importance of gender and developmental context for symptom expression and the utility of structural models to integrate general trends and disorder-specific characteristics.
|
|
| 8. |
- Pahlen, Shandell, et al.
(författare)
-
Age-moderation of genetic and environmental contributions to cognitive functioning in mid- and late-life for specific cognitive abilities
- 2018
-
Ingår i: Intelligence. - : Elsevier. - 0160-2896 .- 1873-7935. ; 68, s. 70-81
-
Tidskriftsartikel (refereegranskat)abstract
- Age moderation of genetic and environmental contributions to Digits Forward, Digits Backward, Block Design, Symbol Digit, Vocabulary, and Synonyms was investigated in a sample of 14,534 twins aged 26 to 98 years. The Interplay of Genes and Environment across Multiple Studies (IGEMS) consortium contributed the sample, which represents nine studies from three countries (USA, Denmark, and Sweden). Average test performance was lower in successively older age groups for all tests. Significant age moderation of additive genetic, shared environmental, and non-shared environmental variance components was observed, but the pattern varied by test. The genetic contribution to phenotypic variance across age was smaller for both Digit Span tests, greater for Synonyms, and stable for Block Design and Symbol Digit. The non-shared environmental contribution was greater with age for the Digit Span tests and Block Design, while the shared environmental component was small for all tests, often more so with age. Vocabulary showed similar age-moderation patterns as Synonyms, but these effects were nonsignificant. Findings are discussed in the context of theories of cognitive aging.
|
|
| 9. |
- Reynolds, Chandra A., et al.
(författare)
-
Gene-Environment Interplay in Physical, Psychological, and Cognitive Domains in Mid to Late Adulthood : Is APOE a Variability Gene?
- 2016
-
Ingår i: Behavior Genetics. - : Springer Nature Switzerland AG. - 0001-8244 .- 1573-3297. ; 46:1, s. 4-19
-
Tidskriftsartikel (refereegranskat)abstract
- Despite emerging interest in gene-environment interaction (GxE) effects, there is a dearth of studies evaluating its potential relevance apart from specific hypothesized environments and biometrical variance trends. Using a monozygotic within-pair approach, we evaluated evidence of G×E for body mass index (BMI), depressive symptoms, and cognition (verbal, spatial, attention, working memory, perceptual speed) in twin studies from four countries. We also evaluated whether APOE is a 'variability gene' across these measures and whether it partly represents the 'G' in G×E effects. In all three domains, G×E effects were pervasive across country and gender, with small-to-moderate effects. Age-cohort trends were generally stable for BMI and depressive symptoms; however, they were variable-with both increasing and decreasing age-cohort trends-for different cognitive measures. Results also suggested that APOE may represent a 'variability gene' for depressive symptoms and spatial reasoning, but not for BMI or other cognitive measures. Hence, additional genes are salient beyond APOE.
|
|
