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Robert Plomin

Publications and source records attributed to Robert Plomin.

At least 19 recordsLinked to original sources
PubMed2026

Robust inference and correlates from genetic associations with personality.

Personality traits describe stable differences in how people think, feel and behave, and how they interact with and experience their social and physical environments1,2. Many questions remain unanswered about associations between DNA and personality traits, such as their robustness, their generalizability and the biological and social pathways through which they act. Here we meta-analyse data across 46 cohorts comprising 611,037 to 1.14 million participants with European-like and African-like genomes for genome-wide association studies (GWAS) of the Big Five personality traits (extraversion, agreeableness, conscientiousness, neuroticism and openness to experience), and data from up to 50,725 participants for within-family GWAS. We identify 1,260 lead genetic variants associated with personality, including 824 novel variants3. Common genetic variants explain a moderate 4.8-9.3% of the variance in measures of each trait, and 9.3-13.3% among instruments with typical measurement reliability. Genetic associations with personality are highly consistent but not identical across geography, reporter (self versus close other), age group and measurement instrument, and we find minimal spousal assortment for personality in recent history. In contrast to many other social and behavioural traits4,5, within-family GWAS and polygenic index analyses indicate that genetic associations with personality are minimally confounded by the shared family environment. Polygenic prediction, genetic correlation and Mendelian randomization analyses indicate that personality traits have widespread, potentially causal associations with consequential behaviours and life outcomes. Overall, we find that the genetic architecture of personality is robustly generalizable, minimally confounded and widely relevant to human experience.

Journal Article↗
PubMed2007

Microarrays.

Microarrays are revolutionizing genetics by making it possible to genotype hundreds of thousands of DNA markers and to assess the expression (RNA transcripts) of all of the genes in the genome. Microarrays are slides the size of a postage stamp that contain millions of DNA sequences to which single-stranded DNA or RNA can hybridize. This miniaturization requires little DNA or RNA and makes the method fast and inexpensive; multiple assays of each target make the method highly accurate. DNA microarrays with hundreds of thousands of DNA markers have made it possible to conduct systematic scans of the entire genome to identify genetic associations with complex disorders or dimensions likely to be influenced by many genes of small effect size. RNA microarrays can provide snapshots of gene expression across all of the genes in the genome at any time in any tissue, which has far-reaching applications such as structural and functional 'genetic neuroimaging' and providing a biological basis for understanding environmental influence.

DNA↗
PubMed2006

Heritability of food preferences in young children.

BACKGROUND: There is persisting interest in the idea that taste preferences are heritable characteristics, but few twin studies have found evidence for a significant genetic component. Small sample sizes and idiosyncratic selection of foods may have contributed to the negative results. We hypothesized that using a larger twin sample and empirical groupings of food types, would give stronger evidence for the heritability of food preferences. OBJECTIVE: We examined the heritability of preferences for four food groups in a sample of young twins. DESIGN: We administered a food preference questionnaire with 95 foods to 214 mothers of same-sex twin pairs (103 monozygotic and 111 dizygotic pairs) aged 4 to 5. 18 foods were excluded because they had been tried by fewer than 25% of the children. Foods were grouped into 'Vegetables', 'Fruits', 'Desserts' and 'Meat and Fish' on the basis of a factor analysis of the preference data. Genetic analyses were carried out on mean liking across these four groups, using model fitting techniques. RESULTS: Over all 77 foods, MZ correlations were higher than DZ correlations for 72 of them, with a higher mean MZ correlation (r = 0.76) than DZ correlation (r = 0.56). Using model fitting techniques with the factor scores, significant heritability estimates were obtained for all four food groups. Heritability was modest for dessert foods (0.20), moderate for vegetables (0.37) and fruits (0.51), and high for liking for protein foods (0.78). Shared environmental effects were strong for desserts, fruits and vegetables, while non-shared environmental influences were low for all four food groups. CONCLUSIONS: These results provide strong evidence for modest heritability of food preferences when using empirically-derived groupings of foods.

Child, Preschool↗
PubMed2006

Generalist genes: implications for the cognitive sciences.

In the 'generalist genes' hypothesis, it is suggested that the same genes affect most cognitive abilities and disabilities. This recently proposed hypothesis is based on considerable multivariate genetic research showing that there is substantial genetic overlap between such broad areas of cognition as language, reading, mathematics and general cognitive ability. We assume that the hypothesis is correct and consider here its implications for cognitive neuroscience. In our opinion, the two key genetic concepts of pleiotropy (in which one gene affects many traits) and polygenicity (in which many genes affect a trait) that underlie the generalist genes hypothesis imply a 'generalist brain'. That is, the genetic input into brain structure and function is general not specific.

Animals↗
PubMed2006

Generalist genes and cognitive neuroscience.

Multivariate genetic research suggests that a single set of genes affects most cognitive abilities and disabilities. This finding already has far-reaching implications for cognitive neuroscience, and will become even more revealing when this - presumably large - set of generalist genes is identified. Similar to other complex disorders and dimensions, molecular genetic research on cognitive abilities and disabilities is adopting genome-wide association strategies. These strategies involve very large samples to detect DNA associations of small effect size using microarrays that simultaneously assess hundreds of thousands of DNA markers. When this set of generalist genes is identified, it can be used to provide solid footholds in the climb towards a systems-level understanding of how genetically driven brain processes work together to affect diverse cognitive abilities and disabilities.

Chromosome Mapping↗
PubMed2006

Genotyping pooled DNA using 100K SNP microarrays: a step towards genomewide association scans.

The identification of quantitative trait loci (QTLs) of small effect size that underlie complex traits poses a particular challenge for geneticists due to the large sample sizes and large numbers of genetic markers required for genomewide association scans. An efficient solution for screening purposes is to combine single nucleotide polymorphism (SNP) microarrays and DNA pooling (SNP-MaP), an approach that has been shown to be valid, reliable and accurate in deriving relative allele frequency estimates from pooled DNA for groups such as cases and controls for 10K SNP microarrays. However, in order to conduct a genomewide association study many more SNP markers are needed. To this end, we assessed the validity and reliability of the SNP-MaP method using Affymetrix GeneChip Mapping 100K Array set. Interpretable results emerged for 95% of the SNPs (nearly 110,000 SNPs). We found that SNP-MaP allele frequency estimates correlated 0.939 with allele frequencies for 97 605 SNPs that were genotyped individually in an independent population; the correlation was 0.971 for 26 SNPs that were genotyped individually for the 1028 individuals used to construct the DNA pools. We conclude that extending the SNP-MaP method to the Affymetrix GeneChip Mapping 100K Array set provides a useful screen of >100,000 SNP markers for QTL association scans.

DNA↗
PubMed2006

Common aetiology for diverse language skills in 4 1/2-year-old twins.

Multivariate genetic analysis was used to examine the genetic and environmental aetiology of the interrelationships of diverse linguistic skills. This study used data from a large sample of 4 1/2-year-old twins who were tested on measures assessing articulation, phonology, grammar, vocabulary, and verbal memory. Phenotypic analysis suggested two latent factors: articulation (2 measures) and general language (the remaining 7), and a genetic model incorporating these factors provided a good fit to the data. Almost all genetic and shared environmental influences on the 9 measures acted through the two latent factors. There was also substantial aetiological overlap between the two latent factors, with a genetic correlation of 0.64 and shared environment correlation of 1.00. We conclude that to a large extent, the same genetic and environmental factors underlie the development of individual differences in a wide range of linguistic skills.

Chi-Square Distribution↗
PubMed2006

Prosocial behavior from early to middle childhood: genetic and environmental influences on stability and change.

Prosocial behavior is important for the functioning of society. This study investigates the extent to which environment shared by family members, nonshared environment, and genetics account for children's prosocial behavior. The prosocial behavior of twins (9,424 pairs) was rated by their parents at the ages of 2, 3, 4, and 7 and by their teachers at age 7. For parent ratings, shared environmental effects decreased from .47 on average at age 2 to .03 at age 7, and genetic effects increased from .32 on average to .61. The finding of weak shared environmental effects and large heritability at age 7 was largely confirmed through the use of teacher ratings. Using longitudinal genetic analyses, the authors conclude that genetic effects account for both change and continuity in prosocial behavior and nonshared environment contributes mainly to change.

Age Factors↗
PubMed2006

Parental discipline and affection and children's prosocial behavior: genetic and environmental links.

The authors investigated genetic and environmental contributions to the relationships between children's (N=9,319 twin pairs) prosocial behavior and parental positivity and negativity toward them. Children's prosocial behavior was rated by parents at ages 3, 4, and 7 and by teachers at age 7. At each age, parents described their feelings and discipline toward each twin. Parental positivity was indexed by positive feelings and positive, non-coercive discipline, and parental negativity was indexed by negative feelings and coercive, punitive discipline. Genetics and the environment both contributed to individual differences in prosocial behavior and in parenting. At all ages, parental positivity correlated positively, and parental negativity correlated negatively with prosocial behavior. Genetic factors largely mediated the negative correlation between prosocial behavior and parental negativity. Shared environmental effects contributed mainly to the positive relationship between prosocial behavior and parental positivity. This pattern was found both cross-sectionally and longitudinally. The findings point to the importance of children's characteristics and of the parent-child relationship in family processes.

Adult↗
PubMed2006

Time to give up on a single explanation for autism.

We argue that there will be no single (genetic or cognitive) cause for the diverse symptoms defining autism. We present recent evidence of behavioral fractionation of social impairment, communication difficulties and rigid and repetitive behaviors. Twin data suggest largely nonoverlapping genes acting on each of these traits. At the cognitive level, too, attempts at a single explanation for the symptoms of autism have failed. Implications for research and treatment are discussed.

Autistic Disorder↗
PubMed2006

Genetic heterogeneity between the three components of the autism spectrum: a twin study.

OBJECTIVE: This study investigated the etiology of autistic-like traits in the general population and the etiological overlap between the three aspects of the triad of impairments (social impairments, communication impairments, restricted repetitive behaviors and interests) that together define autism spectrum disorders. METHOD: Parents of 3,400 8-year-old twin pairs from the Twins Early Development Study completed the Childhood Asperger Syndrome Test, a screening instrument for autism spectrum symptoms in mainstream samples. Genetic model-fitting of categorical and continuous data is reported. RESULTS: High heritability was found for extreme autistic-like traits (0.64-0.92 for various cutoffs) and autistic-like traits as measured on a continuum (0.78-0.81), with no significant shared environmental influences. All three subscales were highly heritable but showed low covariation. In the genetic modeling, distinct genetic influences were identified for the three components. CONCLUSIONS: These results suggest the triad of impairments that define autism spectrum disorders is heterogeneous genetically. Molecular genetic research examining the three components separately may identify different causal pathways for the three components. The analyses give no indication that different genetic processes affect extreme autistic impairments and autistic impairments as measured on a continuum, but this can only be directly tested once genes are identified.

Asperger Syndrome↗
PubMed2006

Phenotypic and genetic overlap between autistic traits at the extremes of the general population.

OBJECTIVE: To investigate children selected from a community sample for showing extreme autistic-like traits and to assess the degree to which these individual traits--social impairments (SIs), communication impairments (CIs), and restricted repetitive behaviors and interests (RRBIs)--are caused by genes and environments, whether all of them are caused by the same genes and environments, and how often they occur together (as required by an autism diagnosis). METHOD: The most extreme-scoring 5% were selected from 3,419 8-year-old pairs in the Twins Early Development Study assessed on the Childhood Asperger Syndrome Test. Phenotypic associations between extreme traits were compared with associations among the full-scale scores. Genetic associations between extreme traits were quantified using bivariate DeFries-Fulker extremes analysis. RESULTS: Phenotypic relationships between extreme SIs, CIs, and RRBIs were modest. There was a degree of genetic overlap between them, but also substantial genetic specificity. CONCLUSIONS: This first twin study assessing the links between extreme individual autistic-like traits (SIs, CIs, and RRBIs) found that all are highly heritable but show modest phenotypic and genetic overlap. This finding concurs with that of an earlier study from the same cohort that showed that a total autistic symptoms score at the extreme showed high heritability and that SIs, CIs, and RRBIs show weak links in the general population. This new finding has relevance for both clinical models and future molecular genetic studies.

Autistic Disorder↗
PubMed2006

Birthweight-discordance and differences in early parenting relate to monozygotic twin differences in behaviour problems and academic achievement at age 7.

This longitudinal monozygotic (MZ) twin differences study explored associations between birthweight and early family environment and teacher-rated behaviour problems and academic achievement at age 7. MZ differences in anxiety, hyperactivity, conduct problems, peer problems and academic achievement correlated significantly with MZ differences in birthweight and early family environment, showing effect sizes of up to 2%. As predicted by earlier research, associations increased at the extremes of discordance, even in a longitudinal, cross-rater design, with effect sizes reaching as high as 12%. As with previous research some of these non-shared environmental (NSE) relationships appeared to operate partly as a function of SES, family chaos and maternal depression. Higher-risk families generally showed stronger negative associations.

Anxiety Disorders↗
PubMed2005

Genotyping DNA pools on microarrays: tackling the QTL problem of large samples and large numbers of SNPs.

BACKGROUND: Quantitative trait locus (QTL) theory predicts that genetic influence on complex traits involves multiple genes of small effect size. To detect QTL associations of small effect size, large samples and systematic screens of thousands of DNA markers are required. An efficient solution is to genotype case and control DNA pools using SNP microarrays. We demonstrate that this is practical using DNA pools of 100 individuals. RESULTS: Using standard microarray protocols for the Affymetrix GeneChip Mapping 10 K Array Xba 131, we show that relative allele signal (RAS) values provide a quantitative index of allele frequencies in pooled DNA that correlate 0.986 with allele frequencies for 104 SNPs that were genotyped individually for 100 individuals. The sensitivity of the assay was demonstrated empirically in a spiking experiment in which 15% and 20% of one individual's DNA was added to a DNA pool. CONCLUSION: We conclude that this approach, which we call SNP-MaP (SNP microarrays and pooling), is rapid, cost effective and promises to be a valuable initial screening method in the hunt for QTLs.

Alleles↗
PubMed2005

SNPs, microarrays and pooled DNA: identification of four loci associated with mild mental impairment in a sample of 6000 children.

Mild mental impairment (MMI) represents the low extreme of the quantitative trait of general intelligence and is highly heritable. Quantitative trait loci (QTLs) conferring susceptibility to MMI, as for most complex traits, are likely to be of small effect size. Using a novel approach we call SNP-MaP (SNP Microarrays and Pooling), we have identified four loci associated with MMI. These four loci have been replicated in two SNP-MaP studies and verified by individual genotyping. The two SNP-MaP studies conducted were a case versus control comparison (n = 515 and n = 1028, respectively) and a low versus high general intelligence extremes group comparison (n = 503 and n = 505, respectively). Each of the four groups consisted of five independent 'subpools', with each subpool assayed on a separate microarray. Twelve loci showing the largest significant differences in both SNP-MaP studies were individually genotyped on 6154 children. Of the four loci positively associated with MMI, the minor allele of each conferred the greater risk for MMI. Two of the loci are close to known genes and may be in linkage disequilibrium with them. One of the loci is between the candidate genes KLF7 and CREB1, but given possible long-range effects on expression and the unknown importance of untranslated elements such as micro-RNAs, all four loci deserve attention as candidates. Although each SNP accounts for a small amount of variance, their effects are additive and they can be combined in a 'SNP set' that can be used as a genetic risk index for MMI in behavioral genomic analyses.

Child↗
PubMed2005

Genetic influences on the stability of attention-deficit/hyperactivity disorder symptoms from early to middle childhood.

BACKGROUND: The high heritability of the core symptoms of attention-deficit/hyperactivity disorder (ADHD) has been repeatedly demonstrated, but few studies to date have investigated the extent to which the same genetic influences operate across development or new genes emerge at different developmental periods. METHODS: We report data from a large, population-based study of approximately 4,000 twin pairs, who have been followed up from early to middle childhood. RESULTS: Parents' ratings of ADHD symptoms showed moderate stability across the ages, which was mainly due to shared genetic influences. There was also evidence of additional genetic influences, which were not shared with those acting earlier on, emerging at later age periods. The contribution of environmental influences to the stability of the ADHD symptoms over time was small. Parents' ratings on the Conners' DSM-IV ADHD subscale at the last assessment point, at an average age of 8 years, did not show the rater contrast effects that were observed in the parents' ratings at earlier ages with briefer measures. Similar estimates of genetic and environmental influences were obtained for girls and boys. CONCLUSIONS: We discuss the implications of the findings for molecular genetic studies on ADHD symptomatology.

Age Factors↗
PubMed2005

Quantitative trait locus analysis of candidate gene alleles associated with attention deficit hyperactivity disorder (ADHD) in five genes: DRD4, DAT1, DRD5, SNAP-25, and 5HT1B.

It has been widely postulated that the categorical diagnosis of attention deficit hyperactivity disorder (ADHD) should be seen as the extreme end of a set of traits quantitatively distributed in the general population. A consequence of this is that the genes associated with DSM-IV ADHD should also influence these underlying traits in non-affected individuals. The aim of this study was to examine if specific candidate loci previously shown to be associated with DSM-IV ADHD, also act as quantitative trait loci (QTLs) for ADHD-symptoms in the general population. We have genotyped five candidate markers in a population-based sample of male dizygous twin-pairs (n = 329 pairs). We found little evidence to support a role for the previously-nominated alleles of a DRD4 VNTR, a 5HT1B SNP, or a microsatellite marker near to DRD5, in the distribution of ADHD-symptoms scores; however, we found some evidence to suggest that the DAT1 3'UTR VNTR and weak evidence that a microsatellite in SNAP-25 may have a role in continuous measures of ADHD-symptoms hyperactivity above and beyond their role in clinical ADHD.

Alleles↗