Night and Day: Are Siblings as Different in Temperament as Parents Say They Are?

Twin studies suggest that parent ratings of temperament exaggerate differences between twins. The present study examined whether such contrast effects also operate for nontwin siblings. The activity level (AL) and shyness of 95 nontwin sibling pairs (ages 3 to 8 years) were assessed via parent ratings and objective measures (actigraph and observer ratings). Siblings showed no resemblance in either parent-rated AL or shyness; however, sibling resemblance for actigraph AL and observer-rated shyness was substantial. Thus, parents do contrast their nontwin siblings when rating these 2 temperament dimensions. Moreover, the importance of sibling differences in temperament to the sibling relationship and differential maternal treatment varied across the different measures of AL and shyness, suggesting that parent perceptions may play a role in these associations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Exploring the genetic and environmental etiology of high general cognitive ability in fourteen- to thirty-six-month-old twins

Two definitions of normality ("isolated" or "correlated") are considered. The boundaries of "isolated" normality were determined by a statistical procedure, whereas the "correlated" approach was related to a clinical or predictive definition. In the latter case, the biological variations were considered abnormal if they implied a hazard with some significant future ailment as a risk factor. In this pragmatic approach, the upper limit of normal/abnormal variations is the point beyond which medical strategy is related to the most expected benefit when applied to a definite population or to an individual patient. The capacity of a diagnostic test to discriminate between patients with a defined risk and those without risk depends strictly on the value of the parameter chosen. In medical care for the prevention of vascular complications in diabetic patients or with foetal risks in pregnant women, the limits of the so-called normal range of glycaemia and other parameters should be determined according to the objective of the preventive and/or therapeutic measures to be prescribed.     

Parent ratings of EAS temperaments in twins, full siblings, half siblings, and step siblings.

A twin/family design was used to explore genetic contributions to personality; to evaluate whether twins and nontwins yield different genetic results; and to test for the presence of contrast effects, the tendency of a rater to contrast one sibling with the other, thereby magnifying existing behavioral differences. The sample consisted of 708 adolescent same-sex sibling pairs from 10 to 18 years of age. Pairs included identical (monozygotic; MZ) and fraternal (dizygotic; DZ) twins, and full siblings in nondivorced families; and full, half, and unrelated siblings in stepfamilies. Mothers and fathers rated the temperament of their children on the EAS Temperament Survey (A. H. Buss & R. Plomin, 1984). Model-fitting analyses revealed significant genetic infiuences on each of the four EAS dimensions; however, for some dimensions, heritability estimates were significantly greater for twins than for nontwins. Overall, the data were best described by a sibling interaction model, which indicated significant contrast effects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Can personality explain genetic influences on life events?

Previous research in the Swedish Adoption/Twin Study of Aging (SATSA) has found genetic influences on life events (R. Plomin et al, see record 1990-14029-001). The present study extends this finding by examining sex differences in genetic and environmental contributions to life events and by examining personality as a mediator of genetic influences on life events in SATSA. Analyses were based on 320 twin pairs, including identical and fraternal twins reared together and apart (mean age 58.6 yrs). Controllable, desirable, and undesirable life events revealed significant genetic variance only for women. There was no significant genetic variance for either sex for uncontrollable events. Multivariate analysis of personality (as indexed by Neuroticism, Extraversion, and Openness to Experience) and life events suggest that all of the genetic variance on controllable, desirable, and undesirable life events for women is common to personality. Thus, in this sample of older adult women, genetic influences on life events appear to be entirely mediated by personality. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Population exposure to electromagnetic fields generated by radio base stations: evaluation of the urban background by using provisional model and instrumental measurements

Electromagnetic radiation, which is used by broadcasting and mobile telephone systems to transmit information, permeates the city environment. In order to properly evaluate population exposure to electromagnetic fields, knowledge of their intensity and spectral components is necessary. In this study the results of radiofrequency field monitoring carried out in Torino, a large town located in the north-west of Italy are shown: the variation of the electromagnetic field strength is evaluated as a function of the height from the ground, the location in the urban area and the frequency. separating the contributions of the different sources (broadcasting antennas and radio base stations for mobile phones). Furthermore, the contribution of the radio base stations is theoretically evaluated, adding the emissions off all installations situated in Torino and examining the field strength maps calculated, considering the orography, for different heights. The theoretical values are also compared with those measured in the frequency range of mobile telephony emissions.     

Molecular Basis of Multiple Mitochondrial Dysfunctions Syndrome 2 Caused by CYS59TYR BOLA3 Mutation

Multiple mitochondrial dysfunctions syndrome (MMDS) is a rare neurodegenerative disorder associated with mutations in genes with a vital role in the biogenesis of mitochondrial [4Fe–4S] proteins. Mutations in one of these genes encoding for BOLA3 protein lead to MMDS type 2 (MMDS2). Recently, a novel phenotype for MMDS2 with complete clinical recovery was observed in a patient containing a novel variant (c.176G > A, p.Cys59Tyr) in compound heterozygosity. In this work, we aimed to rationalize this unique phenotype observed in MMDS2. To do so, we first investigated the structural impact of the Cys59Tyr mutation on BOLA3 by NMR, and then we analyzed how the mutation affects both the formation of a hetero-complex between BOLA3 and its protein partner GLRX5 and the iron–sulfur cluster-binding properties of the hetero-complex by various spectroscopic techniques and by experimentally driven molecular docking. We show that (1) the mutation structurally perturbed the iron–sulfur cluster-binding region of BOLA3, but without abolishing [2Fe–2S]²⁺ cluster-binding on the hetero-complex; (2) tyrosine 59 did not replace cysteine 59 as iron–sulfur cluster ligand; and (3) the mutation promoted the formation of an aberrant apo C59Y BOLA3–GLRX5 complex. All these aspects allowed us to rationalize the unique phenotype observed in MMDS2 caused by Cys59Tyr mutation.     

Stability and change in temperament during adolescence.

This study assessed genetic and environmental contributions to temperament during adolescence within the Nonshared Environment and Adolescent Development project (NEAD; D. Reiss, J. M. Neiderhiser, E. M. Hetherington, & R. Plomin, 2000). NEAD is a national study that includes twins and other sibling types who vary in regard to genetic relatedness. Seven hundred twenty sibling pairs (aged 12.1-13.5 years) participated at Time 1, and 395 sibling pairs (aged 14.7-16.2 years) participated again at Time 2. At both Times, mothers and fathers rated their children's temperament (emotionality, activity, sociability, and shyness). At Times 1 and 2, genetic and nonshared environmental factors accounted for variance in temperament, whereas shared environmental contributions were negligible. However, at Time 1, genetic contributions were inflated, and shared environmental contributions were masked if sibling contrast effects were not taken into account. At Time 2, sibling interaction effects had little impact on estimates of genetic and environmental contributions to temperament. Last, temperament stability was primarily explained by genetic factors, whereas both genetic and nonshared environmental factors accounted for change. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The etiology of behavioral problems and competencies in very young twins.

Although genetic and environmental influences on behavior problems in middle childhood and adolescence have been well-studied, little is known about the etiology of behavior problems in very early childhood. The present study explores genetic and environmental contributions to individual differences in behavior problems and competences in an infant-toddler sample of twins. There were 1,950 twin pairs (mean age=23.8 months) who were rated by parents on the Infant-Toddler Social and Emotional Assessment. All four domains (Externalizing, Internalizing, Dysregulation, Competence) and 20 subscales-indices on the Infant-Toddler Social and Emotional Assessment displayed significant heritability. There were also substantial shared environmental influences operating on most of the domains and subscales. Compared with behavior problems, behavioral competencies were less heritable and more influenced by shared environments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Understanding child-based effects on parenting: Temperament as a moderator of genetic and environmental contributions to parenting.

The degree to which child temperament moderates genetic and environmental contributions to parenting was examined. Participants were drawn from the Nonshared Environment and Adolescent Development project and included 720 sibling pairs, ages 13.5 + 2.0 years (Sibling 1) to 12.1 + 1.3 years (Sibling 2). The sample consisted of 6 sibling types: 93 monozygotic twin pairs, 99 dizygotic twin pairs, and 95 full sibling pairs from never-divorced families and 182 full-sibling, 109 half-sibling, and 130 unrelated-sibling pairs residing in stepfamilies. Composite child temperament ratings (negative emotionality, activity, shyness, and sociability) were derived from mothers' and fathers' reports. Composite parenting ratings (negativity, warmth) for mothers and fathers were generated from children's and parents' reports. Analyses indicated that at higher levels of negative emotionality and sociability, child-based genetic contributions to mothers' and fathers' negativity increased, whereas the contributions of environmental factors declined. The opposite pattern was observed for child shyness. These same characteristics had less impact on parental warmth. For fathers only, nonshared environmental contributions to fathers' warmth increased in the presence of high child activity and sociability but declined when children were very shy. Overall these findings indicate that child-based effects on negative parenting are enhanced when children demonstrate potentially challenging characteristics but are weaker in the absence of such characteristics. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Genetic and environmental origins of verbal and performance components of cognitive delay in 2-year-olds.

The authors investigated the etiology of several measures of cognitive delay. Verbal (V) and performance (P) abilities were assessed in over 3,000 pairs of 2-year-old twins. Group-differences heritability for general delay (the lowest 5% of the V and P composite) was 35%. However, V and P delays considered independently showed large differences in group heritability (77% for V vs. 40% for P). Specific delays with comorbid cases eliminated showed an even greater difference in group heritability (78% vs. 22%, respectively). The small sample comorbid for both V and P delay also yielded high group heritability for both V (77%) and P (93%) scores. Shared environmental factors also differed in magnitude for V (20%) and P (41 %) delays. Because the genetic and environmental origins of V and P delays in infancy differ, they are better considered separately rather than combined into a composite measure of general cognitive delay. (PsycINFO Database Record (c) 2010 APA, all rights reserved)