Simultaneous Selection of Multiple Important Single Nucleotide Polymorphisms in Familial Genome Wide Association Studies Data

We propose a resampling-based fast variable selection technique for selecting important Single Nucleotide Polymorphisms (SNP) in multi-marker mixed effect models used in twin studies. Due to computational complexity, current practice includes testing the effect of one SNP at a time, commonly termed as `single SNP association analysis'. Joint modeling of genetic variants within a gene or pathway may have better power to detect the relevant genetic variants, hence we adapt our recently proposed framework of $e$-values to address this. In this paper, we propose a computationally efficient approach for single SNP detection in families while utilizing information on multiple SNPs simultaneously. We achieve this through improvements in two aspects. First, unlike other model selection techniques, our method only requires training a model with all possible predictors. Second, we utilize a fast and scalable bootstrap procedure that only requires Monte-Carlo sampling to obtain bootstrapped copies of the estimated vector of coefficients. Using this bootstrap sample, we obtain the $e$-value for each SNP, and select SNPs having $e$-values below a threshold. We illustrate through numerical studies that our method is more effective in detecting SNPs associated with a trait than either single-marker analysis using family data or model selection methods that ignore the familial dependency structure. We also use the $e$-values to perform gene-level analysis in nuclear families and detect several SNPs that have been implicated to be associated with alcohol consumption

Emergenesis: Genetic traits that may not run in familes.

Traits that are influenced by a configuration--rather than by a simple sum-- of polymorphic genes may not be seen to be genetic unless one studies monozygotic twins (who share all their genes and thus all gene configurations) because such “emergenic” traits will tend not to run in families. Personal idiosyncrasies that have been found to be surprisingly concordant among MZ twins separated in infancy and reared apart may be emergenic traits. More speculatively, important human traits like leadership, genius in its many manfestations, being an eflective therapist or parent, as well as certain psychopathological syndromes, may also be emergenic. These ideas re-emphasize the importance of the role played in human aflairs by genetic variation

The Determinants of Leadership: The Role of Genetic, Personality, and Cognitive Factors

A sample of 646 male twins (331 monozygotic or identical, 315 dizygotic or fraternal) completed a survey indicating their leadership role occupancy in work settings. Data on these individuals were also available for personality and cognitive variables. As predicted, two personality variables (Social Potency and Achievement) and a cognitive variable (a vocabulary test) were significantly correlated with the leadership variable. Subsequently, univariate and multivariate genetic analyses showed that a substantial portion of this leadership variance was accounted for by genetic factors (39 percent) while non-shared (or non-common) environmental factors accounted for the remaining variance in this leadership variable. Genetic influences were shown for the personality and cognitive factors as well. Finally, results indicated that the genetic influences for the leadership factor were substantially associated with or common with the genetic factors influencing the personality factors, but not with the cognitive variable.

Behavioral Effects of Outdoor Learning on Primary Students

Children have an innate sense of curiosity about nature. “When children come in contact with nature, they reveal their strength” (Montessori, 1967, pg. 69) and therefore, outdoor education can be a useful learning tool for students. Whether being outdoors or bringing the nature-based activities inside, children have the opportunity to work with all of their senses. A growing number of schools around the United States have begun adding outdoor learning to their curriculum (Lieberman & Hoody, 1998) to bring a positive outcome to students’ behavior. Outdoor learning provides another environment that children can thrive in and hopefully benefit from. As many students struggle with learning confined to an indoor learning environment, like most classrooms, changing the environment offers students a uniquely rich context to frame student learning and provides them with movement, stimulation and grabs their attention so they can focus better (Bjorge, Hannah, Rekstad and Pauly, 2017). “If students are more focused, it is less likely for them to cause disruptive behaviors” (Bjorge, et. al, p. 4). This positive change in behavior is beneficial for everyone including students, teachers, and parents. By incorporating outdoor learning regularly in a classroom, children are given the freedom to move and explore on a sensorial level that may promote positive learning abilities. Using the outdoor environment as a classroom setting can have an impact on children who are not successful in an indoor classroom setting. According to existing research, (Bjorge, et. al, 2017; James, J.K. and Williams, T., 2017; Lieberman & Hoody, 1998) student motivation and concentration behaviors, as well as overall well-being, can be greatly impacted and improved through outdoor learning opportunities.

Comparison of academic performance of twins and singletons in adolescence : follow-up study

Objectives To determine whether twins in recent cohorts show similar academic performance in adolescence to singletons and to test the effect of birth weight on academic performance in twins and singletons. Design Follow-up study. Setting Denmark. Participants All twins (n = 3411) and a 5% random sample of singletons (n = 7796) born in Denmark during 1986-8. Main outcome measures Test scores in ninth grade (age 15 or 16), birth weight, gestational age at birth, parents’ age, and parents’ education. Results Ninth grade test scores were normally distributed, with almost identical mean and standard deviations for twins and singletons (8.02 v 8.02 and 1.05 v 1.06) despite the twins weighing on average 908 g (95% confidence interval 886 to 930 g) less than the singletons at birth. Controlling for birth weight, gestational age at birth, age at test, and parents’ age and education confirmed the similarity of test scores for twins and singletons (difference 0.04, 95% confidence interval − 0.03 to 0.10). A significant, positive association between test score and birth weight was observed in both twins and singletons, but the size of the effect was small: 0.06-0.12 standard deviations for every kilogram increase in birth weight. Conclusions Although older cohorts of twins have been found to have lower mean IQ scores than singletons, twins in recent Danish cohorts show similar academic performance in adolescence to that of singletons. Birth weight has a minimal effect on academic performance in recent cohorts; for twins this effect is best judged relative to what is a normal birth weight for twins and not for singletons

Genetic amplification and the individuation of the parent-child relationship across adolescence

BACKGROUND: Many psychological traits become increasingly influenced by genetic factors throughout development, including several which might intuitively be seen as purely environmental characteristics. One such trait is the parent-child relationship, which is associated with a variety of socially significant outcomes, including mental health and criminal behavior. Genetic factors have been shown to partially underlie some of these associations, but the changing role of genetic influence over time remains poorly understood. METHOD: Over 1,000 participants in a longitudinal twin study were assessed at three points across adolescence with a self-report measure regarding the levels of warmth and conflict in their relationships with their parents. These reports were analyzed with a biometric growth curve model to identify changes in genetic and environmental influences over time. RESULTS: Genetic influence on the child-reported relationship with parent increased throughout adolescence, while the relationship’s quality deteriorated. The increase in genetic influence resulted primarily from a positive relation between genetic factors responsible for the initial relationship and those involved in change in the relationship over time. In contrast, environmental factors relating to change were negatively related to those involved in the initial relationship. CONCLUSIONS: The increasing genetic influence appears due to early genetic influences having greater freedom of expression over time, while environmental circumstances were decreasingly important to variance in the parent-child relationship. We infer that the parent-child relationship may become increasingly influenced by the particular characteristics of the child (many of which are genetically-influenced), gradually displacing the effects of parental or societal ideas of child-rearing

Changes in Genetic and Environmental Influences on the Development of Nicotine Dependence and Major Depressive Disorder from Middle Adolescence to Early Adulthood

This longitudinal study used a representative community sample of same-sex twins (485 monozygotic pairs, 271 dizygotic pairs) to study longitudinal changes in genetic and environmental influences on nicotine dependence (NicD) symptoms and major depressive disorder (MDD) symptoms and the longitudinal relationships between NicD and MDD symptoms at three relatively discrete ages spanning middle adolescence to early adulthood (ages 15, 18, and 21). Clinical interviews were used to assess NicD and MDD symptoms lifetime at age 15 and during the previous 3 years at the two subsequent assessments. Biometric models revealed similar patterns of findings for NicD and MDD. Heritability increased with age, particularly between ages 15 and 18. Shared environmental influences were small, and the proportion of variance attributed to shared environmental influences decreased with age. Nonshared environmental influences were moderate to large in magnitude and were entirely age specific. Both NicD and MDD symptoms showed considerable stability from age 15 to 21, and at each age those with one disorder showed elevated rates of the other. However, a cross-lagged model revealed no longitudinal predictive relationships between MDD symptoms and NicD symptoms after accounting for stability of symptoms within disorders. In summary, the transition between middle and late adolescence is a critical period for developmental shifts in the magnitudes of genetic and environmental influences on both MDD and NicD symptoms. Despite similarities in the development of genetic and environmental influences for the two phenotypes, the association between NicD and MDD reflects concurrent covariation rather than one phenotype being an antecedent influence on the subsequent development of the other

Genetic and Environmental Contributions to the Association Between Anthropometric Measures and IQ: A Study of Minnesota Twins at Age 11 and 17

Peer reviewe