Personality can be thought of as a set of characteristics that influence people's thoughts, feelings and behavior across a variety of settings. Variation in personality is predictive of many outcomes in life, including mental health. Here we report on a meta-analysis of genome-wide association (GWA) data for personality in 10 discovery samples (17,375 adults) and five in silico replication samples (3294 adults). All participants were of European ancestry. Personality scores for Neuroticism, Extraversion, Openness to Experience, Agreeableness and Conscientiousness were based on the NEO Five-Factor Inventory. Genotype data of ≈ 2.4M single-nucleotide polymorphisms (SNPs; directly typed and imputed using HapMap data) were available. In the discovery samples, classical association analyses were performed under an additive model followed by meta-analysis using the weighted inverse variance method. Results showed genome-wide significance for Openness to Experience near the RASA1 gene on 5q14.3 (rs1477268 and rs2032794, P=2.8 × 10(-8) and 3.1 × 10(-8)) and for Conscientiousness in the brain-expressed KATNAL2 gene on 18q21.1 (rs2576037, P=4.9 × 10(-8)). We further conducted a gene-based test that confirmed the association of KATNAL2 to Conscientiousness. In silico replication did not, however, show significant associations of the top SNPs with Openness and Conscientiousness, although the direction of effect of the KATNAL2 SNP on Conscientiousness was consistent in all replication samples. Larger scale GWA studies and alternative approaches are required for confirmation of KATNAL2 as a novel gene affecting Conscientiousness.

Personality traits are basic dimensions of behavioral variation, and twin, family, and adoption studies show that around 30% of the between‐individual variation is due to genetic variation. There is rapidly growing interest in understanding the evolutionary basis of this genetic variation. Several evolutionary mechanisms could explain how genetic variation is maintained in traits, and each of these makes predictions in terms of the relative contribution of rare and common genetic variants to personality variation, the magnitude of nonadditive genetic influences, and whether personality is affected by inbreeding. Using genome‐wide single nucleotide polymorphism (SNP) data from > 8000 individuals, we estimated that little variation in the Cloninger personality dimensions (7.2% on average) is due to the combined effect of common, additive genetic variants across the genome, suggesting that most heritable variation in personality is due to rare variant effects and/or a combination of dominance and epistasis. Furthermore, higher levels of inbreeding were associated with less socially desirable personality trait levels in three of the four personality dimensions. These findings are consistent with genetic variation in personality traits having been maintained by mutation–selection balance.

The longitudinal stability of personality is low in childhood but increases substantially into adulthood. Theoretical explanations for this trend differ in the emphasis placed on intrinsic maturation and socializing influences. To what extent does the increasing stability of personality result from the continuity and crystallization of genetically influenced individual differences, and to what extent does the increasing stability of life experiences explain increases in personality trait stability? Behavioral genetic studies, which decompose longitudinal stability into sources associated with genetic and environmental variation, can help to address this question. We aggregated effect sizes from 24 longitudinal behavioral genetic studies containing information on a total of 21,057 sibling pairs from 6 types that varied in terms of genetic relatedness and ranged in age from infancy to old age. A combination of linear and nonlinear meta-analytic regression models were used to evaluate age trends in levels of heritability and environmentality, stabilities of genetic and environmental effects, and the contributions of genetic and environmental effects to overall phenotypic stability. Both the genetic and environmental influences on personality increase in stability with age. The contribution of genetic effects to phenotypic stability is moderate in magnitude and relatively constant with age, in part because of small-to-moderate decreases in the heritability of personality over child development that offset increases in genetic stability. In contrast, the contribution of environmental effects to phenotypic stability increases from near zero in early childhood to moderate in adulthood. The life-span trend of increasing phenotypic stability, therefore, predominantly results from environmental mechanisms.

<h4>Background</h4>Personality traits, particularly Conscientiousness, are recognised as crucial psychological factors contributing to success in elite-level athletes. Emerging evidence suggests that individual differences in these traits are influenced by environmental exposure and genetic variation, especially within the dopaminergic system. The <i>DRD2</i> promoter polymorphism rs1799732, which affects dopamine D2 receptor expression, may modulate goal-directed behaviour and self-regulation traits.<h4>Methods</h4>This study included 323 participants (141 elite mixed martial arts (MMA) athletes and 182 non-athlete controls). Participants completed the NEO Five-Factor Inventory (NEO-FFI). Genotyping for the <i>DRD2</i> rs1799732 polymorphism was conducted using real-time PCR. Group comparisons and two-way ANOVA were used to assess genotype-phenotype associations and gene × environment interactions.<h4>Results</h4>Athletes scored significantly higher on Conscientiousness than controls. A significant main effect of the DRD2 rs1799732 genotype and a genotype × group interaction were observed for Conscientiousness. Specifically, athletes with the ins/ins genotype exhibited the highest levels of Conscientiousness, whereas individuals with the del/del genotype showed the lowest scores. No significant associations were found for other personality traits.<h4>Conclusions</h4>These findings suggest that the DRD2 promoter polymorphism rs1799732 moderates the expression of Conscientiousness, particularly under the structured and demanding conditions experienced by elite athletes. Our results support a gene × environment interaction model, highlighting the importance of considering genetic predispositions in high-performance environments. These insights may inform personalised psychological support strategies tailored to athletes' genetic profiles, enhancing motivation, self-regulation and long-term athletic development.

Human dopamine transporter gene (SLC6A3) is one of the neurotransmission genes that plays an important role in controlling the behavior and psychological reactions toward various physical activities. The aim of the present study is to evaluate the associations between SLC6A3 3’-UTR VNTR (3’VNTR) genotypes and eight personality traits in Egyptian athletes. One hundred athletes (50 males and 50 females) and one hundred non-athletes participated in this investigation either in individual or team games. The Freiburg Personality inventory-Revised questionnaire was applied to athletes to evaluate personality traits according to the scale, at a scheduled time, using descriptive analysis. Genotyping for SLC6A3 3’-UTR VNTR polymorphism in athletes was realized to detect the different genotypes by PCR amplifications using desired primers. Three different genotypes of the 3’VNTR polymorphism; namely (9/9), (9/10), (10/10) were identified. The 9/10 and 10/10 genotypes of SLC6A3 gene were significantly higher in players than those in the control group. There were no statistically significant differences in personality traits values among males and females. The Cronbach’s alpha stability coefficient for four items is higher than 0.7 suggesting that these items (Neuroticism, Aggressiveness, Depression and Excitability) have a good reliability and support the used personality dimensions for this investigation. Our findings revealed a significant association between the genotypes of 3’VNTR and the personality traits in Egyptian athletes. These data shed light on the role of SLC6A3 gene in athletes’ behavioral performance and could serve as the basis for further characterization in the large number of Egyptian athletes.

I investigated the genetic and environmental etiology of individual differences in a variety of complex human behaviours, broadly captured within three domains - 1) cannabis use, 2) personality, and 3) sexuality and mating. Research questions and hypotheses are addressed with large community-based, genetically informative datasets and various methodological and statistical approaches. Section I focuses on the genetics of cannabis use. By meta-analysing existing twin studies I determined more precisely the relative contributions of genes and environment on individual differences in cannabis use and abuse. For cannabis use initiation I found a heritability estimate of 48% in males and 40% in females. For problematic cannabis use the heritability estimates were 51% and 59% for males and females. I then performed a gene-based association test on a large sample to test for genetic association between ten previously reported candidate genes and lifetime frequency of cannabis use. None of the candidate genes reached even nominal significance, which may point to our limited understanding of the neurobiology of cannabis use and also to potential publication bias and false-positive findings in previous studies. To identify potential new genetic variants underlying cannabis use, I then meta-analysed results from two large genome-wide association studies for cannabis use initiation. I did not identify any genetic variant significantly contributing to cannabis use initiation. Furthermore,

Abstract Human personality is 30–60% heritable according to twin and adoption studies. Hundreds of genetic variants are expected to influence its complex development, but few have been identified. We used a machine learning method for genome-wide association studies (GWAS) to uncover complex genotypic–phenotypic networks and environmental interactions. The Temperament and Character Inventory (TCI) measured the self-regulatory components of personality critical for health (i.e., the character traits of self-directedness, cooperativeness, and self-transcendence). In a discovery sample of 2149 healthy Finns, we identified sets of single-nucleotide polymorphisms (SNPs) that cluster within particular individuals (i.e., SNP sets) regardless of phenotype. Second, we identified five clusters of people with distinct profiles of character traits regardless of genotype. Third, we found 42 SNP sets that identified 727 gene loci and were significantly associated with one or more of the character profiles. Each character profile was related to different SNP sets with distinct molecular processes and neuronal functions. Environmental influences measured in childhood and adulthood had small but significant effects. We confirmed the replicability of 95% of the 42 SNP sets in healthy Korean and German samples, as well as their associations with character. The identified SNPs explained nearly all the heritability expected for character in each sample (50 to 58%). We conclude that self-regulator

Males and females score differently on some personality traits, but the underlying etiology of these differences is not well understood. This study examined genetic, environmental, and prenatal hormonal influences on individual differences in personality masculinity–femininity (M-F). We used Big-Five personality inventory data of 9,520 Swedish twins (aged 27 to 54) to create a bipolar M-F personality scale. Using biometrical twin modeling, we estimated the influence of genetic and environmental factors on individual differences in a M-F personality score. Furthermore, we tested whether prenatal hormone transfer may influence individuals’ M-F scores by comparing the scores of twins with a same-sex versus those with an opposite-sex co-twin. On average, males scored 1.09 standard deviations higher than females on the created M-F scale. Around a third of the variation in M-F personality score was attributable to genetic factors, while family environmental factors had no influence. Males and females from opposite-sex pairs scored significantly more masculine (both approximately 0.1 SD ) than those from same-sex pairs. In conclusion, genetic influences explain part of the individual differences in personality M-F, and hormone transfer from the male to the female twin during pregnancy may increase the level of masculinization in females. Additional well-powered studies are needed to clarify this association and determine the underlying mechanisms in both sexes.

Human behavior is shaped by psychological traits, as personality types vary from person to person, producing different actions and behavior. Human behavior Human behavior is the potential and expressed capacity (mentally, physically, and socially) of human individuals or groups to respond to internal and external stimuli throughout their life. Behavior is driven by environmental and genetic factors that affect an individual. Behavior is also driven, in part, by thoughts and feelings, which provide insight into individual psyche, revealing such things Human… Human behavior encompasses a vast array of domains that span the entirety of human experience. Social behavior involves interactions between individuals and groups , while cultural behavior reflects the diverse patterns, values, and practices that vary across societies and historical periods.Moral behavior… Perso…

intelligence 240 PERSONALITY TRAITS 243 Breeding for temperament in animals 243 Human personality traits 247 SEXUAL … multiple traits. Two traits generate 16 possible equally likely out comes. Note that individual traits generate … Examples of quan- titative behavioral traits include personality traits, intelligence, and some psy- chopathologies