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Longitudinal as well as cross-sectional studies have shown variations with age in heritability estimates for body dimensions from infancy to adulthood, even though the patterns of variation are not completely clear. Further study on this subject is of great interest and may help obesity interventions for preventing or treating obesity in children. Therefore, the aim of the present study is to analyse the changes in the genetic and environmental architecture of 8 body linearity and obesity-related phenotypes during the growth process in a cross-sectional sample of 1018 nuclear families from the province of Biscay (Basque Country, Spain). The contribution of additive genetic effects to the variation of the analysed traits was estimated by a variance component analysis using the SOLAR program. Moderate to high heritability estimates were obtained for all 8 anthropometric phenotypes (38.23-65.98%). The heritability values show an increasing trend with age and in the course of the entire ontogenetic development two age periods were remarkable. At 7(+)-8(+) years of age a strong increase in heritability estimates was found for all the anthropometric phenotypes, except for the sum of skinfolds (SF6), reflecting the biological significance of genes during mid-childhood. During puberty, most of the obesity related phenotypes showed their highest heritability values while linear measurements and weight presented a decrease in the genetic contributions. In conclusion, this study confirms that additive genetic influences have a considerable effect on body linearity and obesity-related traits throughout the growth period and that mid-childhood and puberty are very sensitive periods in human life cycle., (Copyright © 2012 Elsevier GmbH. All rights reserved.)

The major objective of this study was to determine the possible effects of common genetic and environmental factors among 18 craniofacial anthropometric traits, with special attention to the differences between skeletal and soft-tissue related phenotypes. The studied sample consisted of 122 nuclear families living in Brussels and included 251 males and 258 females aged from 13 to 72 years. Univariate and bivariate quantitative genetic analyses were performed using a variance components procedure implemented in SOLAR software. All phenotypes were significantly influenced by additive genetic factors with heritability estimates ranging from 0.46 (nose height) to 0.72 (external biocular breadth). Sex, age and their interactions explained 7-46% of the total phenotypic variance of the traits. Bivariate analysis revealed that several traits share a common genetic and/or environmental basis while other traits show genetic and environmental independence from one another. More and greater genetic and environmental correlations were observed among skeletal phenotypes, than among soft-tissue traits and between both categories. Apart from the tissue composition, other characteristics of the craniofacial morphology such as the orientation (e.g. heights, breadths) have shown to be important factors in determining pleiotropy and common environmental effects between some pairs of traits. In conclusion, the results confirm that overall head configuration is largely determined by additive genetic effects, and that common genetic and environmental factors affecting craniofacial size and shape are stronger for the skeletal traits than for the soft-tissue traits., (Copyright 2010 Elsevier GmbH. All rights reserved.)

The aim of the present study was to examine the heritability of 11 traits in a mixed-longitudinal sample of Indian siblings, and to determine whether heritability estimates vary during the growth period and whether they are influenced by sex. The sample consisted of 245 brothers and 213 sisters from 138 nuclear families living in a semi-urban area in Kolkata, India. The age ranged between 5 and 19 years. The traits were standardised for age and sex using standard deviation scores (SDS) produced by the LMS method (Cole, T.J., 1988. Fitting smoothed centile curves to reference data. J. R. Stat. Soc. A 151, 385-418). The standard deviation scores were analysed by PCA. The two factors with eigenvalues above 1 explained 77.3% of the variance; they showed a high level of pleiotropism present among the studied traits and represented body lengths (PC1) and body weight and breadths (PC2). The heritability between all types of siblings (irrespective of sex) for the PC1 and PC2 was estimated. The heritability between various pairs of siblings showed variations along the whole ontogenetic period studied. During the childhood and pre-pubertal period, heritability between brothers, brother-sister pairs and any sibling pairs was mostly constant, with small and non-significant variations. All the pairs showed the lowest degree of heritability during puberty for PC1 but not for PC2, with significant changes of heritability estimates between adolescence and adulthood, in most of the analysed sibling pairs and in both PC factors. The highest heritability was generally observed at the end of the examined growth period in all pairs. A significant effect of sex on heritability was only detected for PC2 at 11 years of age.

The anthropometric somatotype is a quantitative description of body shape and composition. Familial studies indicate the existence of a familial resemblance for this phenotype and they suggest a substantial action by genetic factors on this aggregation. The aim of this study is to examine the degree of familial resemblance of the somatotype components and of a factor of shape, in a sample of Biscay nuclear families (Basque Country, Spain). One thousand three hundred and thirty nuclear families were analysed. The anthropometric somatotype components [Carter, J.E.L., Heath, B.H., 1990. Somatotyping. Development and applications. Cambridge University Press, Cambridge, p. 503] were computed. Each component was fitted for the other two through a stepwise multiple regression, and also fitted through the LMS method [Cole, T., 1988. Fitting smoothed centile curves to reference data. J. Roy. Stat. Soc. 151, 385-418] in order to eliminate the age, sex and generation effects. The three raw components were introduced in a PCA from which a shape factor (PC1) was extracted for each generation. The correlations analysis was performed with the SEGPATH package [Province, M.A., Rao, D.C., 1995. General purpose model and computer programme for combined segregation and path analysis (SEGPATH): automatically creating computer from symbolic language model specifications. Genet. Epidemiol. 12, 203-219]. A general model of transmission and nine reduced models were tested. Maximal heritability was estimated with the formula of [Rice, T., Warwick, D.E., Gagnon, J., Bouchard, C., Leon, A.S., Skinner, J.S., Wilmore, J.H., Rao, D.C., 1997. Familial resemblance for body composition measures: the HERITAGE family study. Obes. Res. 5, 557-562]. The correlations were higher between offspring than in parents and offspring and a significant resemblance between mating partners existed. Maximum heritabilities were 55%, 52% and 46% for endomorphy, mesomorphy and ectomorphy, respectively, and 52% for PC1. In conclusion, the somatotype presents a moderate degree of familial aggregation. For the somatotype components, as well as for PC1, the degree of familial resemblance depends on age. The sex only has a significant effect on ectomorphy.

The present research analyses a cross-sectional sample of 284 individuals (86 fathers, 86 mothers, 54 sons and 58 daughters) in 86 nuclear families living in the province of Biscay (Basque Country, Spain), with the aim of estimating both transmissible and non-transmissible components acting on familial resemblance for the maximum dynamometric strength of both hands, by means of a path analysis. Standardised data of each generation and sex were adjusted to a BETA model of path analysis independent of sex effects, allowing nevertheless the possibility to differentiate between transmissible (genetic and cultural) and non-transmissible (environmental) components acting on the observed phenotypic variance in Biscayan offspring. The results supported the full model of familial transmission for the two variables, in addition to other reduced models that gave rise to transmission effects regardless of any influence from the siblings' shared environment on the environmental transmitted component from their parents (b = 0), and without social homogamy between mates (u = 0). The most parsimonious model created, based on the previous ones, was accepted for both traits. The total transmissible variance (t2) explained between 21% (right hand) and 44% (left hand) of the observed phenotypic variation. These values are close to those from the literature (t2 = 37%). However, we should take into account that these kinds of estimations are specific for each group or population.

The present study was based on a cross-sectional sample of 1326 subjects (197 fathers, 466 mothers, 307 sons and 356 daughters) belonging to 488 nuclear families from the province of Biscay (Basque Country, Spain), with the purpose of estimating the degree of familial resemblance, for several anthropometric traits, by analysing the correlation coefficients between parent-offspring pairs. Height, weight, biacromial and bicrystal breadths, humerus and femur biepicondylar breadths, arm, waist and hip circumferences, biceps, triceps, subscapular, suprailiac, abdominal, thigh and calf skinfolds were taken from each individual. BMI, WHR and the sum of the seven skinfolds was computed. The mother's occupation and the age of offspring were taken into account, since the combination of all these factors might have an effect on familial resemblance. The mothers were classified into housewife (HM) and working mothers (WM). The offspring were divided into prepuberal, puberal and postpuberal subgroups. Standardised residuals were used to compute father-offspring (FO) and mother-offspring (MO) relations through correlation coefficients computed by maximum likelihood. The results confirm the influence of age on the correlations, since FO correlations revealed an increasing trend in HM's children for weight and another six variables as they grew older. On the other hand, the weight change tends to decrease with age in FO correlations within the WM group. Depending on mother's occupation and children's age, the global trend in the sample results in higher correlations in the second group (WM) than in the first one (HM) for the whole age range, but specially in FO correlations before puberty, where four variables (weight, bicrystal breadth, triceps and subscapular skinfolds) yield statistically significant differences.