Sibling Correlations Research Articles

Familial resemblance of physical activity levels in the Portuguese population

Moderate to high levels of physical activity are related to positive health status. Parents share with their children important cultural aspects and beliefs related to healthy living. However, family studies show contradictory results for familial aggregation of physical activity. The purposes of this study were to assess whether physical activity shows familial aggregation in the Portuguese population and to disentangle the exact pattern of familial resemblance. Cross-sectional family study. We sampled 2661 Portuguese nuclear families (10,644 subjects) and assessed their physical activity using the Baecke questionnaire, including components for physical activity work/school, leisure-time activity, sports participation, and a total index of physical activity. Generalized estimating equations were used to compute spousal, parent-offspring and sibling correlations. For leisure-time activity and total index of physical activity, the patterns were characterized with spouse correlations higher than parent-offspring correlations (0.20 vs 0.12, p=0.001 and 0.22 vs 0.12, p=10(-4), respectively) but lower than those in offspring (0.20 vs 0.51, p<10(-4) and 0.22 vs 0.35, p<10(-4), respectively). For sports participation, the spouse correlation was higher than parent-offspring correlations (0.30 vs 0.18, p<10(-4)), but also higher than sibling correlations (0.30 vs 0.22, p<10(-4)). Finally, the physical activity work/school spouse correlation was higher than the sibling correlations (0.22 vs 0.12, p<10(-4)). The results support the hypothesis of familial aggregation in physical activity. Further, fathers and mothers had a similar influence on their offspring's physical activity levels irrespective of their sex, and equal sibling correlations point toward shared physical activity habits.

Family influence in fertility: A longitudinal analysis of sibling correlations in first birth risk and completed fertility among Swedish men and women

BACKGROUND The intergenerational transmission of fertility has received much attention in demography. This has been done by estimating the correlation between parents' and offsprings' fertility. An ...

Merkel cell polyomavirus infection occurs during early childhood and is transmitted between siblings

Merkel cell polyomavirus (MCPyV) is thought to be the etiological agent of Merkel cell carcinoma, but little is known about its distribution and modes of transmission. We conducted seroepidemiological surveys in more than 1000 individuals, from two populations from Cameroon. Overall MCPyV seroprevalence was high in both populations (>75% in adults). Data from the first population, comprising mainly children, indicated that MCPyV infections mostly occurred during early childhood, after the disappearance of specific maternal antibodies. Results from the second family-based population provided evidence for familial aggregation of MCPyV infection status. We observed significant sib–sib correlation (odds ratio=3.42 [95% CI 1.27–9.19], p=0.014), particularly for siblings close together in age, and a trend for mother–child correlation (OR=2.71 [0.86–8.44], p=0.08). Overall, our results suggest that MCPyV infection is acquired through close contact, possibly involving saliva and/or the skin, especially between young siblings and between mothers and their children.

How important is the family? Evidence from sibling correlations in permanent earnings in the USA, Germany, and Denmark

This paper is the first to analyze the impact of family background on permanent earnings based on sibling correlations in Germany and to provide a cross-country comparison of Germany, Denmark, and USA. The main findings are that family and community background has a stronger influence on permanent earnings in Germany than in Denmark, and a comparable influence is found in USA. This holds true for both male and female siblings. A deeper analysis of Germany shows that family background also plays an important role in explaining variations in family income, wages, education, and risk attitudes.

Genetic analysis of egg quality traits in White Leghorn chicken

Aim: The present study was undertaken to estimate the genetic parameters and to assess the inheritance pattern of egg quality traits in White Leghorns. Materials and Methods: Data on 480 eggs produced by 40 week old pullets of 4 genetic groups were used for studying egg quality traits. Heritabilities and correlations were estimated by full sib correlation method using Mixed Model Least Squares and Maximum Likelihood (LSMLMW) computer program. Results: The egg weight, haugh unit, yolk index, albumen index, yolk weight, albumen weight, shell weight and shell thickness ranged from 50.01 ± 0.48 to 53.89 ± 0.43 g, 65.38 ± 0.92 to 80.98 ± 1.01, 0.341 ± 0.003 to 0.353 ± 0.003, 0.056 ± 0.002 to 0.087 ± 0.002, 14.16 ± 0.13 to 15.58 ± 0.12 g, 30.92 ± 0.39 to 33.18 ± 0.39 g, 4.32 ± 0.05 to 5.12 ± 0.05 g and 0.336 ± 0.003 to 0.376 ± 0.003 mm, respectively. Heritability estimates for egg weight, yolk index, albumen index and albumen weight ranged from low to medium while those of haugh unit, yolk weight, shell weight and shell thickness ranged from low to high. The genetic and phenotypic correlations of egg weight with other egg quality traits except shell quality traits were mostly positive and moderate to high. High positive genetic and phenotypic correlations between haugh unit and other traits were observed. Genetic correlation of yolk weight with albumen weight was positive while that with shell quality traits was mostly negative. Shell weight was positively correlated with shell thickness. Conclusion: Significant genetic group differences were observed for various egg quality traits studied. The heritability estimates for different egg quality traits were low to moderate. The association among egg quality traits was positive in general.

Book Reviews

Bhash Mazumder of Federal Reserve Bank of Chicago reviews, “Heredity, Family, and Inequality: A Critique of Social Sciences” by Michael Beenstock. The EconLit Abstract of this book begins: “Explores the roles of heredity, family, and social environment in the determination of outcomes among humans, including anthropometric, psychological, behavioral, and economic outcomes. Discusses the apple and the tree—Francis Galton revisited; correlation within the family; explaining the intergenerational and sibling correlations; inequality, diversity, and family; empirical methodology; empirical knowledge on the causes of correlations within the family; where we go from here; statistics; parenting theory and child behavior; and empirical methodology. Beenstock is Professor of Economics at the Hebrew University of Jerusalem. Bibliography; index.”

Heredity, family, and inequality: a critique of social sciences

Empirical literature in disciplines ranging from behavioral genetics to economics shows that in virtually every aspect of life the outcomes of children are correlated to a greater or lesser extent with the outcomes of their parents and their siblings. In Heredity, Family, and Inequality, the economist Michael Beenstock offers theoretical, statistical, and methodological tools for understanding these correlations. Beenstock presents a comprehensive survey of intergenerational and sibling correlations for a broad range of outcomes -- including fertility and longevity, intelligence and education, income and consumption, and deviancy and religiosity. He then offers a critique of the sometimes conflicting explanations for these correlations proposed by social scientists from such disciplines as developmental psychology, sociology, and economics. Beenstock also provides an axiomatic framework for thinking about the complex interplay of heredity, family, and environments, drawing on game theory, control theory, and econometrics. Chapters 1-7 discuss such topics as the important contributions of Francis Galton (1822--1911) to the statistical study of heredity, the family as an engine of inequality and diversity, and natural experiments designed to identify how environments, families, peer groups, and neighborhoods affect human outcomes. Chapters 8-10 present technical material on statistical, theoretical, and methodological tools used by the earlier chapters. Beenstock's goal is not to argue for either nature or nurture but to suggest more rigorous ways to assess the diverse contributions to this lively debate.

The Life Course Variation of Sibling Correlations According to Class and Education

How does the influence of family background vary over the life course? This question is studied through sibling correlations using Finnish Census based register data, including information on 57,050 children born 1956-1970. The applied data includes information on the education (as levels and years in education) and occupational status (as EGP-classes and ISEI scores) of the siblings, measured twice between the ages of 20-29, 25-34, 30-39 and 35-44 during the period 1970-2005. Children are matched according to the education and class their parents belonged to when the siblings were 10-14 years old. According to the results, the family background effect does not change much over the life course. The variations in education and occupational standing increase both at the family and individual level, as the siblings grow older. Also, there was no socioeconomic background bias due to parents treating their children differently. The correlations are the highest when education is measured as levels (~0.5); it remains at the level of 0.3 for other dependent variables. However, the proportion of the variation explained by the observed parental characteristics is about the same for each type of status measurement. This suggests that the estimates for the total family background effect across the different types of socioeconomic measurements are not directly comparable even when applying sibling correlations.

GENETIC AND ENVIRONMENTAL INFLUENCES ON BLOOD PRESSURE IN AN URBAN INDIAN POPULATION

Aggarwal Baniyas were found to have a high prevalence of high blood pressure. Genetic and environmental influences may be implicated for this risk factor of cardiovascular disease. The aim of this study was to investigate the potential for common genetic and environmental influences on blood pressure measures (systolic and diastolic blood pressure (SBP, DBP)). The population-based sample was comprised of 309 Aggarwal Baniya families, including 1214 individuals (271 fathers, 307 mothers, 311 sons and 325 daughters) from New Delhi, India. The prevalence of obesity in this community was found to be high (BMI: fathers, 26.1 kg/m2; mothers, 29.4 kg/m2; sons, 16.9-22.4 kg/m2; and daughters, 16.3-22.7 kg/m2). Correlation and heritability were estimated. Most sibling-sibling correlations were larger than the parent-offspring correlations, and all parent-offspring and sibling-sibling correlations were larger than the corresponding spouse correlation (SBP=0.026; DBP=0.029). The maximum heritability was estimated as 44.6% for SBP and 62.8% for DBP. The lack of a significant spouse correlation is consistent with little or no influence of the common familial environment. However, the high heritability estimate for both SBP and DBPs reinforces the importance of the non-shared environmental effect.

Heritability and Genome-Wide Association Study to Assess Genetic Differences between Advanced Age-related Macular Degeneration Subtypes

To investigate whether the 2 subtypes of advanced age-related macular degeneration (AMD), choroidal neovascularization (CNV), and geographic atrophy (GA) segregate separately in families and to identify which genetic variants are associated with these 2 subtypes. Sibling correlation study and genome-wide association study (GWAS). For the sibling correlation study, 209 sibling pairs with advanced AMD were included. For the GWAS, 2594 participants with advanced AMD subtypes and 4134 controls were included. Replication cohorts included 5383 advanced AMD participants and 15 240 controls. Participants had the AMD grade assigned based on fundus photography, examination, or both. To determine heritability of advanced AMD subtypes, a sibling correlation study was performed. For the GWAS, genome-wide genotyping was conducted and 6 036 699 single nucleotide polymorphisms (SNPs) were imputed. Then, the SNPs were analyzed with a generalized linear model controlling for genotyping platform and genetic ancestry. The most significant associations were evaluated in independent cohorts. Concordance of advanced AMD subtypes in sibling pairs and associations between SNPs with GA and CNV advanced AMD subtypes. The difference between the observed and expected proportion of siblings concordant for the same subtype of advanced AMD was different to a statistically significant degree (P = 4.2 × 10(-5)), meaning that in siblings of probands with CNV or GA, the same advanced subtype is more likely to develop. In the analysis comparing participants with CNV to those with GA, a statistically significant association was observed at the ARMS2/HTRA1 locus (rs10490924; odds ratio [OR], 1.47; P = 4.3 × 10(-9)), which was confirmed in the replication samples (OR, 1.38; P = 7.4 × 10(-14) for combined discovery and replication analysis). Whether CNV versus GA develops in a patient with AMD is determined in part by genetic variation. In this large GWAS meta-analysis and replication analysis, the ARMS2/HTRA1 locus confers increased risk for both advanced AMD subtypes, but imparts greater risk for CNV than for GA. This locus explains a small proportion of the excess sibling correlation for advanced AMD subtype. Other loci were detected with suggestive associations that differ for advanced AMD subtypes and deserve follow-up in additional studies.

How important is family background for labor-economic outcomes?

This paper uses Swedish register data to examine four classical outcomes in empirical labor economics: IQ, noncognitive skills, years of schooling and long-run earnings. We estimate sibling correlations – and the variance components that define the sibling correlation – in these outcomes. We also estimate correlations for MZ-twins, who share all genes. We also extend the variance-component decomposition by accounting for birth order. We find that conventional intergenerational approaches severely underestimate the role of family background, and that future research should follow a more multidimensional approach to the study of family background.

Intra-familial aggregation and heritability of aortic versus brachial pulse pressure after imputing pretreatment values in a community of African ancestry

To compare the intra-familial aggregation and heritability of central (aortic) (PPc) versus peripheral (brachial) (PPp) pulse pressure after imputing pretreatment blood pressures (BPs) in treated participants in a community of black African ancestry. Central PPc [generalized transfer function (GTF) and radial P2-derived] was determined with applanation tonometry at the radial artery (SphygmoCor software) in 946 participants from 258 families with 23 families including three generations from an urban developing community of black Africans. In the 24.1% of participants receiving antihypertensive treatment, pretreatment brachial BP was imputed from published overall averaged effects of therapy grouped by class and dose, specific for groups of black African descent. From these data PPc was estimated from proportionate differences in central aortic and brachial PP. Heritability estimates were determined from SAGE software. Echocardiography was evaluated in 507 participants in order to determine stroke volume. With adjustments for confounders, parent-child (P < 0.05) and sibling-sibling (P < 0.0005) correlations were noted for log PPc, whilst for log PPp only sibling-sibling correlations were noted. No mother-father correlations were noted for either PPc or PPp. Independent of confounders the heritability for log GTF-derived (h = 0.33 ± 0.07, P < 0.0001) and P2-derived (h = 0.30 ± 0.07, P < 0.0001) PPc was greater than the heritability for log PPp (h = 0.11 ± 0.06, P < 0.05) (P < 0.05 for comparison of heritability estimates). After imputing pretreatment BP values, central aortic PP is significantly more inherited than brachial PP. These data suggest that in groups of African descent the genetic determinants of PP may be underestimated when employing brachial rather than central aortic PP measurements.

Exploring the factors contributing to sibling correlations in BMI: a study using the Panel Study of Income Dynamics.

Understanding the mechanisms contributing to correlated BMI outcomes in a social network such as siblings will help policy makers reduce the burden of disease associated with obesity. There are two potential mechanisms explaining correlated BMI outcomes in a biologically related social network: (i) time constant factors such as genetic heritability and habits formed during childhood and (ii) factors that change over time some of which are dependent on the frequency of interactions between the social network, for example, social norms shaped by the social network's shifting attitudes towards weight and behaviors related to weight, or environmental factors like opportunities for exercise. This study aims to distinguish between time constant factors from factors that are likely to change over time to gain a better understanding of the mechanisms explaining the correlation in sibling BMI. We exploit data from the Panel Study of Income Dynamics (PSID) over 1999–2007 estimating the correlation in BMI for adult siblings who currently live in separate households but grew-up in the same household and adolescent siblings currently living in the same household to isolate the influence of factors that change over time. The findings indicate that time constant factors explain some of the overall correlation in sibling BMI for both cohorts of siblings. Factors that change over time only significantly impact on the overall correlation in BMI for adolescent siblings suggesting if there is a social network influence on correlations in BMI this is facilitated by sharing the same household.

Gender, Geography and Generations: Intergenerational Educational Mobility in Post-Reform India

India experienced sustained economic growth for more than two decades following the economic liberalization in 1991. While economic growth reduced poverty significantly, it was also associated with an increase in inequality. Does this increase in inequality reflect deep-seated inequality of opportunity or efficient incentive structure in a market oriented economy? This paper provides evidence on economic mobility in post-reform India by focusing on educational attainment of children. We use two related measures of immobility: sibling and intergenerational correlations. We analyze the trends in and patterns of educational mobility from 1992/93 to 2006, with a special emphasis on the roles played by gender and geography. The evidence shows that family background plays a strong role; the estimated sibling correlation in India in 2006 is higher than the available estimates for Latin American countries. There is a persistent gender gap in rural and less-developed areas. The only group that experienced substantial improvements is women in urban and developed areas. Men experienced little or no upward mobility. Almost 70 percent of the variance in children’s education can be accounted for by parental education and geographic location. We provide possible explanations for the apparently puzzling improvements for urban women in a country with strong son preference.

Estimasi Parameter Genetik Sifat Produksi Sapi Simmental di Balai Pembibitan Ternak Unggul Sapi Potong Padang Mengatas, Sumatera Barat (Estimation of Genetic Parameters of Production Characteristics on Simmental Cattle at Balai Pembibitan Ternak Unggulan

&lt;p&gt;The objectives of this research were to estimate the genetic parameters of production characteristics, breeding value (BV), weaning weight ratio (WWR) correlation with BV and most probable producing ability (MPPA) of Simmental cattle reared at Balai Pembibitan Ternak Unggul Sapi Potong Padang Mengatas. Research was based on records of birth weight (BW), weaning weight (WW), post weaning average daily gain (ADG) and yearling weight (YW) from 2002 to 2007. Heritability value (h2) was estimated for BV, WW, ADG and YW using paternal-half sib correlation and repeatability value (r) of characteristics of both using intra class correlation. The genetic correlation (rG) of BW-WW, WW-YW, WW-ADG, WW-YW, WW-ADG and YW-ADG were analyzed by variance and covariance. BV and MPPA estimation was base on record of weaning weight. The h2 value of BW, WW, YW and ADG were 0.11±0.09; 0.39±0.16; 0.43±0.19; and 0.46±0.20, respectively. The r of BW, WW, YW and ADG, were 0.25±0.16; 0.32±0.18; 0.25±0.22; and 0.34±0.16, respectively. The genetic correlation value of BW-WW, WW-YW, WW-ADG, WW-YW, WW-ADG and YW-ADG were 0.29±0.37; 0.46±0.33; 0.2 ±0.39; 0.68±0.16; 0.006±0.30 and 0.57±0.21, respectively. From 18 Bulls, 10 bulls (55.56%) had the BV higher then average population value, 142.21 kg and the remaining 8 bulls (44.44%) was lower then average population value. Frequency of the BV of prospective male and female with WW higher than WW average was 210 calves (44.68%); whereas, 260 calves (55.32%) had WW lower than average population corrected with parent age (130.21 kg). Range of absolute BV was from 112.77 kg to 155.91 kg. The BV of male had average frequency higher than that of female, i.e. 149 males (66.22%) compared to 61 female (24.90%). The MPPA with above the average WW of the population was 150 cows (41.67%) and the rest of cows (210 head or 58.33%) were under the&lt;br /&gt;average. The WWR had positive and significant correlation (1.00**) with the NP. It means that, if the cattle have a high WWR, they will also have a high NP, so that they can be used as the criteria of selection.&lt;/p&gt;&lt;p&gt;(Key words: Simmental cattle, Genetic parameters, Breeding value, Most probable producing ability, Weaning weight ratio)&lt;br /&gt;&lt;br /&gt;&lt;/p&gt;

Health Dynamics and the Evolution of Health Inequality over the Life Course: The Importance of Neighborhood and Family Background

Abstract This paper investigates the extent and ways in which childhood family and neighborhood quality influence later-life health outcomes. The study analyzes the health trajectories of children born between 1950 and 1970 followed through 2005. Data from the Panel Study of Income Dynamics (PSID) spanning four decades are linked with information on neighborhood attributes and school quality resources that prevailed at the time these children were growing up.There are several key findings. First, estimates of sibling and child neighbor correlations in health are used to bound the proportion of inequality in health status in childhood through mid-life that are attributable to childhood family and neighborhood quality. Estimates based on four-level hierarchical random effects models (neighborhoods, families, individuals, over time) consistently show a significant scope for both childhood family and neighborhood background (including school quality). The results imply substantial persistence in health status across generations that are linked in part to low intergenerational economic mobility. Sibling correlations are large throughout at least the first 50 years of life: roughly three-fifths of adult health disparities may be attributable to family and neighborhood background. Childhood neighbor correlations in adult health are also substantial (net of the similarity arising from similar family characteristics), suggesting that disparities in neighborhood background account for more than one-third of the variation in health status in mid life.Second, exposure to concentrated neighborhood poverty during childhood has significant deleterious impacts on adult health. The results reveal that even a large amount of selection on unobservable factors does not eliminate the significant effect of child neighborhood poverty on health status later in life. Thus, racial differences in adult health can be accounted for by childhood family, neighborhood, and school quality factors, while contemporaneous economic factors account for relatively little of this gap.

Alike in Many Ways: Intergenerational and Sibling Correlations of Brothers' Earnings

We model the correlations of brothers’ life-cycle earnings separating for the first time the effect of paternal earnings from additional residual sibling effects. We identify the two effects by analysing sibling correlations and intergenerational correlations jointly within a unified framework. Our multi-person model of earnings dynamics distinguishes permanent earnings from transitory –serially correlated—shocks, allows for life-cycle effects and nests the models of previous research that have focussed either on intergenerational or sibling correlations. Using data on the Danish population of father/first-son/second-son triplets we find that sibling effects explain between one fourth and one half of inequality in life-cycle earnings, and largely account for individual differences in earnings growth. Intergenerational associations account for a considerable share of overall sibling correlations, between 30 and 60 per cent from youth to maturity. We also find that transitory shocks are correlated across family members, in particular between brothers. Extensions of the model show a distinctive effect of mothers’ human capital on top of fathers’ earnings and no evidence of differential intergenerational transmission between brothers.

Familial aggregation of allergen‐specific sensitization and asthma

Familial aggregation of specific response to allergens and asthma adjusted for age and sensitization to multiple allergens was assessed in two large population cohorts. Allergen skin prick tests (SPTs) were administered to 1151 families in the Tucson Children's Respiratory Study (CRS) and 435 families in the Tucson Epidemiological Study of Airway Obstructive Disease (TESAOD). Sensitization was defined by wheal size ≥3 mm; physician-diagnosed asthma at age ≥8 yr was based on questionnaires. Using S.A.G.E. 6.1 software ASSOC and FCOR, familial correlations of crude and adjusted phenotypes were evaluated. Crude estimates of parent-offspring (P-O) and sibling correlations were statistically significant for most allergens, ranging from 0.03 to 0.29. After adjusting for age of assessment and 'other atopy' (SPT-positive response to additional allergens), correlations were reduced by 14-71%. Sibling correlations for specific response to allergens were consistently higher than P-O correlations, but this difference was significant only for dust mite and weed mix in the TESAOD population. Familial correlation for atopic status (any positive SPTs vs. none) tended to be higher than for specific allergens. Asthma, with and without adjustment, showed greater familial correlation than either specific or general SPT response and significantly higher sibling correlation in TESAOD than in CRS, probably due to the older age of the siblings and the longer period of ascertainment. Significant familial aggregation of specific response to allergen after adjustment for other atopy appears to reflect a genetic propensity toward atopy, dependent on shared familial exposures. Results also suggest that inheritance of asthma is independent of atopic sensitization.

Family and Community Influences on Health and Socioeconomic Status: Sibling Correlations Over the Life Course

This paper presents new estimates of sibling correlations in health and socioeconomic outcomes over the life course in the U.S. Sibling correlations provide an omnibus measure of the importance of all family and community influences. I find that sibling correlations in a range of health and socioeconomic outcomes start quite high at birth and remain high over the life course. The sibling correlation in birth weight is estimated to be 0.5. Sibling correlations in test scores during childhood are as high as 0.6. Sibling correlations in adult men's wages are also around 0.5. Decompositions provide suggestive evidence on which pathways may account for the gradients in health and SES by family background. For example, sibling correlations in cognitive skills and non-cognitive skills during childhood are lower controlling for family income. Similarly, parent education levels can account for a sizable portion of the correlation in adult health status among brothers.

Attrition in Models of Intergenerational Links Using the PSID with Extensions to Health and to Sibling Models.

Selective attrition potentially biases estimation of intergenerational links in health and economic status. This paper documents attrition in the PSID through 2007 for a cohort of children, and investigates attrition bias in intergenerational models predicting adult health, education and earnings, including models based on sibling differences. Although attrition affects unconditional means, the weighted PSID generally maintains its representativeness along key dimensions in comparison to the National Health Interview Survey. Using PSID, sibling correlations in outcomes and father-son correlations in earnings are not significantly affected by attrition. Models of intergenerational links with covariates yield more mixed results with females showing few robust impacts of attrition and males showing potential attrition bias for education and earnings outcomes. For adult health outcomes conditional on child background, neither gender shows significant impacts of attrition for the age ranges and models considered here. Sibling models do not produce robustly higher attrition impacts than individual models.