Suchergebnisse

AbstractOne of Nick's key early achievements at QIMR was to establish a twin study on melanoma risk factors. The Brisbane Twin Nevus Study (BTNS) had an initial focus on nevus (mole) count in adolescents but, reflecting Nick's broad interests, expanded in scope enormously over the decades. In the skin cancer arena, BTNS was essential to genetic discoveries in melanoma, eye color and pigmentation. Later studies amassed data on thousands of phenotypes, ranging from molecular phenotypes such as gene expression to studies where gene mapping findings in adolescents turned out to have translational potential in late-onset diseases. Nick's twin data have formed the basis for an enormous range of discoveries, with Nick and his colleagues continuing to capitalize on these data.

The objective of the current study was to investigate the heritability of breast size and the degree to which this heritability is shared with BMI. In a sample of 1010 females twins (mean age 35 years;SD= 2.1; range 28–40), self-report data pertaining to bra cup size and body mass index (BMI) was collected in the context of self-report data and an interview relating to disordered eating respectively. In a sample of 348 complete twin pairs who completed data collection (226 MZ pairs and 122 DZ pairs and 360 incomplete pairs (170 MZ and 190 DZ)), we found that the heritability of bra cup size was 56%. Of this genetic variance, one third is in common with genes influencing body mass index, and two thirds (41% of total variance) is unique to breast size, with some directional evidence of non-additive genetic variation. The implications of these findings with respect to previous research linking breast size with reproductive potential are discussed.

AbstractRecent studies in Asian populations have identified variants in theEDARandFGFR2genes that arose following the divergence of Asians and Europeans and are associated with thick straight hair. To date no genetic variants have been identified influencing hair texture in Europeans. In the current study we examined the heritability of hair curliness in three unselected samples of predominantly European ancestry (NS1= 2717;NS2= 3904;NS3= 5079). When rated using a three point scale (Straight/Wavy/Curly) males were ~5% more likely to report straight hair than females and there were suggestions in the data that curliness increased slightly with age. Across samples significant additive and dominant genetic influences were detected resulting in a broad sense heritability of 85–95%. Given the magnitude and the specificity of the EDAR effect on hair morphology in Asian populations we are hopeful that future association studies will detect similar genetic influences in European populations.

AbstractThe purpose of the present study was to examine the 10 value types from the Portrait Values Questionnaire (PVQ; Schwartz et al., 2001) both at the phenotypic (observed) level as well as the genetic and environmental level. Australian twins (N= 695) completed the PVQ as part of a larger questionnaire battery. Nine of the value types were found to have a genetic component with heritability estimates ranging from 10.8% for power to 38% for conformity. The achievement scale was best explained by environmental factors. The interscale correlations were found to range from –.02 to .70 at the phenotypic level. Of these 45 correlations, 16 were found to be explained by overlapping genetic factors and almost all (41) were found to have significant unique environment correlations.

The purpose of the present study was to do a psychometric evaluation of the somatic and psychological health report (SPHERE) among Chinese adolescents. Our participants were 116 twins (50 females). Psychometric evaluation indicated that the reliability and validity of this scale were good. The internal consistencies and split-half reliabilities of all subscales were above 0.80. Furthermore, the item-total correlations were acceptable for all the subscales (all the values were higher than 0.20). The present findings suggest that the SPHERE can be well used to measure Chinese adolescents' somatic and psychological health.

There has been almost no overlap between behavior genetics and consumer behavior research, despite each field's importance in understanding society. In particular, both have neglected to study genetic influences on consumer adoption and usage of new technologies — even technologies as important as the mobile phone, now used by 5.8 out of 7.0 billion people on earth. To start filling this gap, we analyzed self-reported mobile phone use, intelligence, and personality traits in two samples of Australian teenaged twins (mean ages 14.2 and 15.6 years), totaling 1,036 individuals. ACE modeling using Mx software showed substantial heritabilities for how often teens make voice calls (.60 and .34 in samples 1 and 2, respectively) and for how often they send text messages (.53 and. 50). Shared family environment – including neighborhood, social class, parental education, and parental income (i.e., the generosity of calling plans that parents can afford for their teens) — had much weaker effects. Multivariate modeling based on cross-twin, cross-trait correlations showed negative genetic correlations between talking/texting frequency and intelligence (around –.17), and positive genetic correlations between talking/texting frequency and extraversion (about .20 to .40). Our results have implications for assessing the risks of mobile phone use such as radiofrequency field (RF) exposure and driving accidents, for studying adoption and use of other emerging technologies, for understanding the genetic architecture of the cognitive and personality traits that predict consumer behavior, and for challenging the common assumption that consumer behavior is shaped entirely by culture, media, and family environment.

Disordered gambling (DG) will soon be included along with the substance use disorders in a revised diagnostic category of the Diagnostic and Statistical Manual of Mental Disorders DSM-5 called 'Substance Use and Addictive Disorders'. This was premised in part on the common etiologies of DG and the substance use disorders. Using data from the national community-based Australian Twin Registry, we used biometric model fitting to examine the extent to which the genetic liabilities for DG and alcohol use disorder (AUD) were shared, and whether this differed for men and women. The effect of using categorical versus dimensional DG and AUD phenotypes was explored, as was the effect of using diagnoses based on the DSM-IV and the proposed DSM-5 diagnostic criteria. The genetic correlations between DG and AUD ranged from 0.29 to 0.44. There was a significantly larger genetic correlation between DG and AUD among men than women when using dimensional phenotypes. Overall, about one-half to two-thirds of the association between DG and AUD was due to a shared genetic vulnerability. This study represents one of the few empirical demonstrations of an overlap in the genetic risk for DG and another substance-related addictive disorder. More research is needed on the genetic overlap between DG and other substance use disorders, as well as the genetic overlap between DG and other (non-substance-related) psychiatric disorders.

AbstractTwo major challenges to conducting a community-based twin study of pathological gambling (PG) disorder are that: (a) it is relatively rare, and (b) individuals with the disorder in the community may be difficult to locate and recruit. We describe a new study of 4,764 individuals recruited from the Australian Twin Registry in which we attempt to effectively deal with the first challenge and examine the impact of the second challenge. The lifetime prevalence of DSM-IV PG in this Australian twin sample was 2.2%, which is 400–500% higher than has been obtained in prevalence surveys conducted in the United States. A number of predictors of non-participation were identified, including a lifetime PG disorder diagnosis, but these did not have a large net effect on the estimated number of individuals with PG or related characteristics in the twin sample. Results of biometric modeling suggested that the effect of genetic, shared family environmental, and nonshared environmental influences on the propensity to engage in 11 different specific forms of gambling (e.g., playing the lottery, betting on horse or dog races, playing electronic gaming machines) were generally moderate, low, and moderate, respectively, with mean parameter estimates obtained of 43%, 10%, and 46%. An intriguing comparison with results from a 1963 US adolescent twin study conducted by Loehlin and Nichols (1976) suggests that: (a) propensity genes for gambling involvement may be more likely to be expressed in the heavy-gambling Australian culture, or that (b) the family environment has a transient effect on the gambling behavior of young people.

The perception of sweetness varies among individuals but the sources of this variation are not fully understood. Here, in a sample of 1,901 adolescent and young adults (53.8% female; 243 MZ and 452 DZ twin pairs, 511 unpaired individuals; mean age 16.2 ± 2.8, range 12–26 years), we studied the variation in the perception of sweetness intensity of two monosaccharides and two high-potency sweeteners: glucose, fructose, neohesperidine dihydrochalcone (NHDC), and aspartame. Perceived intensity for all sweeteners decreased with age (2–5% per year) and increased with the history of otitis media (6–9%). Males rated aspartame slightly stronger than females (7%). We found similar heritabilities for sugars (glucose: h2 = 0.31, fructose: h2 = 0.34) and high-potency sweeteners (NHDC: h2 = 0.31, aspartame: h2 = 0.30); all were in the modest range. Multivariate modeling showed that a common genetic factor accounted for >75% of the genetic variance in the four sweeteners, suggesting that individual differences in perceived sweet intensity, which are partly due to genetic factors, may be attributed to a single set of genes. This study provided evidence of the shared genetic pathways between the perception of sugars and high-potency sweeteners.

A propensity to believe that fellow citizens will not act against our interests in social and economic transactions has been identified as key to the effective functioning of democratic polities. Yet the causes of this type of 'generalized' or 'social' trust are far from clear. To date, researchers within the social and political sciences have focused almost exclusively on social-developmental and political/institutional features of individuals and societies as the primary causal influences. In this paper we investigate the intriguing possibility that social trust might have a genetic, as well as an environmental basis. We use data collected from samples of monozygotic and dizygotic twins to estimate the additive genetic, shared environmental, and non-shared environmental components of trust. Our results show that the majority of the variance in a multi-item trust scale is accounted for by an additive genetic factor. On the other hand, the environmental influences experienced in common by sibling pairs have no discernable effect; the only environmental influences appear to be those that are unique to the individual. Our findings problematise the widely held view that the development of social trust occurs through a process of familial socialization at an early stage of the life course. Adapted from the source document.