Brothers delay menarche and the onset of sexual activity in their sisters

The higher costs of sons compared with daughters extends to a negative effect of brothers on the lifetime reproductive success of their siblings in subsistence and preindustrial societies. In societies with fewer resource constraints, one might expect that these effects would be limited or non-existent. This study investigates the costs of brothers and sisters in a contemporary western society of adult Australians. Girls with elder brothers had a delayed age at menarche. Younger brothers were associated with delayed onset of sexual activity in sisters, but not in brothers. Neither younger nor elder brothers influenced fitness parameters (number of pregnancies, number of children, age at first pregnancy or age at first birth) in siblings of either sex. This study provides evidence that brothers negatively affect their sisters'' onset of reproductive maturity and sexual activity; however, this delay is not associated with a fitness cost in contemporary Australia. We suggest this is due to the long period of independence prior to child bearing.     

Brothers and sisters

Data from the Kipsigis of Kenya are used to test two models for how parents invest in offspring, the Trivers-Willard and local resource competition/enhancement hypotheses. Investment is measured as age-specific survival, educational success, marital arrangements, and some components of property inheritance, permitting an evaluation of how biases persist or alter over the period of dependence. Changes through time in such biases are also examined. Despite stronger effects of wealth on the reproductive success of men than women, the survival of sons and daughters is not related to parental wealth. However, a Trivers-Willard effect characterizes educational investment: poor families show a greater concern for daughters’ (vis-à-vis sons’) schooling than do rich families, a trend that has increased over time. In regard to models of local resource competition and enhancement, men’s reproductive success decreases with number of brothers and increases with number of sisters; this pattern of competition with same-sex sibs and cooperation with opposite-sex sibs is not found among women. As predicted from these observations, parents show reduced investment in sons with a large number of brothers, and increased investment in sons with a large number of sisters. By contrast, investment in daughters is entirely unaffected by number of sisters and is influenced only in subtle ways by number of brothers. Levels of investment in relation to sibship size (irrespective of siblings’ sex) are highest for younger children of large sib sets. Discussion of the results in relation to those from other studies leads to three conclusions. First, predictive models for how investment biases vary across societies must consider a broad range of socioecological factors constraining parental options and payoffs. Second, the timing of investment biases within societies will be affected by the value of children and the costs of parental investment. Third, measures of investment appropriate for between-sex and between-class comparisons need careful attention. Each of these issues is brought to bear on the question of why, in contrast to so many other parts of the world, sex preferences are so muted in Africa.     

Prevalence and familial patterns of night eating in the Québec adipose and lifestyle investigation in youth (QUALITY) study

The prevalence and familial patterns of night eating syndrome (NES) in families enrolled in the Québec Adipose and Lifestyle InvesTigation in Youth (QUALITY) study was examined. Families (n = 395; one child, mother, and father for whom at least one parent was obese or had abdominal obesity) completed the Night Eating Questionnaire (NEQ) as part of a longitudinal study on the development of metabolic disease in children at risk for obesity. Responses on the NEQ were used to establish a diagnosis of NES and to determine the correlation and heritability of NES symptoms in families. Using comprehensive research diagnostic criteria, full threshold NES was rare: 0% of children, 0.5% of mothers, and 0.3% of fathers met criteria. When controlling for age, sex, and BMI, NEQ scores of spouses were not significantly correlated, but mothers' NEQ scores were significantly correlated with the scores of both sons (r = 0.19, P < 0.001) and daughters (r = 0.15, P = 0.05). The heritability of NEQ scores was 0.24 when controlling for age, sex, and BMI. These findings replicate previous research suggesting a low prevalence of night eating behavior in children and the aggregation of NES in families.     

What happens to offspring when parents are inbred,old or had a poor start in life? Evidence for sex‐specific parental effects

Parental effects on offspring performance have been attributed to many factors such as parental age, size and condition. However, we know little about how these different parental characteristics interact to determine parental effects, or the extent to which their effect on offspring depends on either the sex of the parent or that of the offspring. Here we experimentally tested for effects of variation in parents’ early diet and inbreeding levels, as well as effects of parental age, and for potential interactive effects of these three factors on key aspects of offspring development in the mosquitofish (Gambusia holbrooki). Older mothers produced offspring that were significantly smaller at birth. This negative effect of maternal age on offspring size was still evident at maturation as older mothers had smaller daughters, but not smaller sons. The daughters of older mothers did, however, reach maturity sooner. Paternal age did not affect offspring body size, but it had a complex effect on their sons’ relative genital size. When initially raised on a food‐restricted diet, older fathers sired sons with relatively smaller genitalia, but when fathers were initially raised on a control diet their sons had relatively larger genitalia. The inbreeding status of mothers and fathers had no significant effects on any of the measured offspring traits. Our results indicate that the manifestation of parental effects can be complex. It can vary with both parent and offspring sex; can change over an offspring's life; and is sometimes evident as an interaction between different parental traits. Understanding this complexity will be important to predict the role of parental effects in adaptation.     

Intrafamilial correlation analysis for IgM serum levels.

The IgM serum level was determined in the members of 29 healthy families. The IgM mean concentrations between fathers and mothers and between sons and daughters were significantly different (P less than .01), with higher serum IgM levels in females than in males. Simple linear regression analysis was done for the following intrafamilial combinations: son-father, daughter-father, son-mother, and daughter-mother. Significant correlation coefficients (P less than .05) were obtained in all four combinations, which does not support the X-linked gene hypothesis (i.e., that the X chromosome carries quantitative genes for immunoglobulin M). An alternative explanation for the differences between sexes for IgM serum concentration is considered.     

Family resemblance for anthropometric traits II. Assessment of maternal occupational and age effects

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.     

Familial aggregation in lone atrial fibrillation

Atrial fibrillation (AF) is the most common clinical arrhythmia and a major risk factor for stroke. To investigate the role of genetic factors in a typical clinical population, we determined the extent of familial aggregation in patients with lone AF. To estimate the relative risk to family members, the prevalence of AF for each class of relative was compared to the prevalence in the comparable age and sex group from the general population. Family members had an increased relative risk of AF compared to the general population (risk ratio; 95% confidence intervals): sons (8.1; 2.0–32), daughters (9.5; 1.3–67), brothers (70; 47–102), sisters (34; 14–80), mothers (4.0; 2.5–6.5) and fathers (2.0; 1.2–3.6). Relatives of probands with lone AF are at a substantially increased risk of developing this arrhythmia suggesting a Mendelian genetic contribution to the etiology of this common trait.     

The role of fathers in mammalian sex allocation

Parents should bias resource allocation towards the sex most likely to provide higher fitness returns by adjusting the birth sex ratio and/or through differential care of sons and daughters. Sex allocation research in mammals to date has been focused almost exclusively on maternal traits, but fathers may also play an important role. Future studies should investigate the influence of paternal quality on the fitness of sons and daughters, and possible conflicts of interest between mothers and fathers. There is also a crucial need for more studies examining whether relative levels of maternal care in sons and daughters depend on paternal quality.     

X-linked inheritance of Alport syndrome: family P revisited.

Likelihood analysis using two autosomal/X-linked mixed models confirmed that Alport syndrome is an X-linked dominant disease in a large Utah kindred, family P. The penetrance was estimated as .85 in females and 1.0 in males. Previously reported abnormal segregation ratios were reexamined. No excess of affected offspring of affected parents was found. Nor was the penetrance in daughters of asymptomatic carrier mothers found to be lower than in the daughters of symptomatic mothers, although the sample size was small. However, there was an unexplained deficiency of sons of affected fathers. There was no deficiency of sons of affected mothers, nor was there a deficiency of males in the kindred.     

Case-control study of whether subfertility in men is familial.

OBJECTIVE--To test the hypothesis that subfertility in men is familial and to examine the distribution of subfertility within families for consistency with a genetic cause. DESIGN--Case-control study and segregation analysis. SETTING--Two teaching hospitals in Leeds. SUBJECTS--Cases (probands) were men with an abnormal sperm count who attended a subfertility clinic and whose partners had no major factor contravening fertility. Controls were fathers of two or more children recruited through vasectomy clinics or a maternity department. MAIN OUTCOME MEASURES--The incidence of involuntary childlessness among brothers with partners and among sisters and second and third degree male relatives. When possible clinical and laboratory details were obtained from involuntarily childless brothers. RESULTS--Seventeen of the 148 (11.5%) brothers of probands but none of the 169 brothers of controls had sought medical advice for childlessness (P < 0.0005). Four probands had more than one involuntarily childless brother. There were six further brothers whose childlessness was thought to be involuntary bringing the total prevalence of subfertility among brothers of probands to 16%. Segregation analysis was consistent with an autosomal recessive mode of inheritance accounting for 60% of subfertility in men. Seventeen of the 346 (4.9%) uncles of probands and 10 of 420 (2.8%) uncles of controls were reported to be involuntarily childless (P = 0.09), but there was no difference in childlessness among sisters. In three families sperm counts from "affected" brothers confirmed the diagnosis and showed considerable similarities within but not between families. CONCLUSION--Subfertility in men has a familial component, and the observations are consistent with an autosomal recessive mode of inheritance in over half the cases. Several different genes are probably involved.     

Transmission of parental care behavior in African striped mice, Rhabdomys Pumilio

The expression of behavior, including parental care behavior, is influenced by complex interactions of the genes of an organism and the prevailing environmental conditions. Previously, we showed that the development of paternal, but not maternal, care in the African striped mouse, Rhabdomys pumilio, has a significant nongenetic maternal component. Here, we investigate the genetic component of parental care behavior from parents to offspring. We first measured the duration of parental care behavior of mothers and fathers every second day for 11 days postnatally. Subsequently, one son and one daughter from each of these litters were paired with unrelated mates when they were adults and their parental care behavior scored. Using regression models, we then compared parental care behavior of parents and their adult offspring. The transmission of parental care behavior from striped mouse fathers to sons and from mothers to both sons and daughters did not indicate a genetic component. Instead, we found a patrilineal genetic component for parental care in daughters. The reason for this unusual pattern of inheritance is not known, but this finding complements that of our other studies, showing that the expression of maternal care behavior in adult daughters is also not nongenetically influenced by their mothers. We suggest that, although females are constrained to provide maternal care in different social contexts, maternal care behavior may be influenced genetically by the father.     

Sex-specific maternal effects in a viviparous fish

Mothers vary in their effects on their offspring, but studies of variation in maternal effects rarely ask whether differences between mothers are consistent for sons and daughters. Here, we analysed maternal effects in the mosquitofish Gambusia holbrooki for development time and adult size of sons and daughters, and a primary male sexual character (gonopodium length). We found substantial maternal effects on all traits, most notably for gonopodium length. There were significant correlations within each sex for maternal effects on different traits, indicative of trade-offs between development rate and adult size. By contrast, there was no evidence of any consistency in maternal effects on sons and daughters. This suggests that the evolution of maternal effects will follow independent trajectories dependent on sex-specific selection on offspring. Importantly, failure to recognize the sex-specific nature of maternal effects in this population would have substantially underestimated the extent of their variation between mothers.     

Allocation of accumulated resources among close kin: Inheritance in Sacramento,California, 1890–1984

We analyze the legacies of 1538 testate decedents from Sacramento, California 1890–1984. Spouse and/or children received an average 92% of the state. The few women who were survived by a spouse more often excluded their husbands in favor of their children than did husbands exclude wives. We explain this difference in spousal treatment in terms of the reproductive potential of the two sexes at the average age of death. Fathers and mothers without spouses bequeathed the majority of assets to children. Seventy-one percent of parents with two or more children treated them absolutely equally. Sex ratio among offspring was equal. There was no evidence of a general sex preference or a wealth by sex-preference interaction. Decedents with two or more daughters treated them more equitably than did decedents with two or more sons— additional evidence that treatment of daughters is less subject to environmental and individual variation than is the treatment of sons. Decedents without biological children treated adopted children like biological children. Smaller legacies to the few adopted children in families with biological children can be explained by increased sibship size.     

The Primary Parental Investment in Children in the Contemporary USA is Education

This paper tests the Trivers-Willard hypothesis that high-status individuals will invest more in sons and low-status individuals will invest more in daughters using data from the 2000 to 2010 General Social Survey and the 1979 National Longitudinal Survey of Youth. We argue that the primary investment U.S. parents make in their children is in their children’s education, and this investment is facilitated by a diverse market of educational choices at every educational level. We examine two measures of this investment: children’s years of education and the highest degree attained. Results show that sons of high-status fathers receive more years of education and higher degrees than daughters, whereas daughters of low-status fathers receive more years of education and higher degrees than sons. Further analyses of possible mechanisms for these findings yield null results. We also find that males are more likely to have high-status fathers than females.     

Parent-offspring correlations in pedometer-assessed physical activity

Background

Physical activity is a major component of a healthy lifestyle in youth and adults. To identify determinants of this complex behavior is an important research objective in the process of designing interventions to promote physical activity at population level. In addition to individual determinants, there is evidence documenting familial influences on physical activity. However, the few studies that have addressed this issue with objective measures did not provide data on parent-offspring physical activity relationships throughout childhood and adolescence. The purpose of this study was to assess familial correlations in pedometer-assessed physical activity.

Methods

We measured ambulatory activity in 286 French nuclear families (283 mothers, 237 fathers, and 631 children aged 8–18 years) by pedometer recordings (Yamax Digiwalker DW 450) over a week. Correlations were computed with their 95% confidence intervals (CI) for spouse pairs, siblings, mother-offspring, and father-offspring. Data were expressed as steps per day and computed both for the full recording period and separately for weekdays and weekends.

Results

The correlations were the highest between siblings (r = 0.28, 95%CI: 0.17–0.38). Parent–offspring correlations were significant in mothers (r = 0.21, 95%CI: 0.12–0.30), especially between mothers and daughters (r = 0.24, 95%CI: 0.12–0.36 vs. r = 0.18, 95%CI: 0.05–0.31 for sons), but were almost nonexistent in fathers. Correlations were generally higher on weekend days compared to weekdays. Mother-offspring correlations did not decrease with increasing age of children (r = 0.17, 95%CI: 0.00–0.34 in 8–11-year-olds, r = 0.20, 95%CI: 0.07–0.33 in 12–15-year-olds, and r = 0.25, 95%CI: 0.07–0.39 in ≥16-year-olds). Finally, between-spouse correlations were significant only during weekend days (r = 0.14, 95%CI: 0.01–0.27).

Conclusion

Ambulatory activity correlated within families, with a possible mother effect. Mother-offspring correlations remained significant through the transition from childhood to adolescence. Further studies are required to better understand the respective influences of shared activities, parental modeling and support as well as genetic factors on the familial aggregation of physical activity.     

Patrilineal family values,family planning and variation in stature among Taiwanese six-year-olds

It has been argued that patrilineal joint family systems tend to bias family planning decisions in favour of sons. A simple model suggests that in such societies, any given son will be more highly valued by his parents (1) the fewer his brothers and (2) the earlier his birth is in the brother series. A daughter's value will be greater (1) the fewer brothers she has and (2) the earlier her birth is relative to other sisters. This study first addresses the extent of son preference as inferred from family composition data for 772 Taiwanese first-graders born in the mid-1970s in two socioeconomically distinct communities in Taipei, Taiwan. It then uses linear regression to consider whether the model criteria help account for statural variation among children in each study area when controlling for differences in measurement age, parental education and housing. With respect to family composition and gender preference, available evidence was consistent with previous surveys. While better-educated parents in the more affluent study area had significantly fewer children (p < 0.0005) and were more willing to stop without a son, girls there, as in the less affluent area, were still significantly more likely than boys to belong to large sibships (p < or = 0.005). Evidence from mean height of males and females partially accords with hypothetical predictions. In the less affluent area, the interaction effect of male birth order and the presence of younger siblings was significantly associated with mean stature (p = 0.002). Males without brothers were 2.0 cm taller than males with either an older or a younger brother (116.3 +/- 0.5 cm vs 114.3 +/- 0.4 cm). Males who had both younger and older brothers, but often no sisters, were about as tall, however, as those without brothers. A similar, but less pronounced, pattern was found among males in the more affluent area, but only among those who had sisters. These boys were also consistently shorter than boys without sisters (115.6 +/- 0.6 cm vs 117.7 +/- 0.6 cm; p = 0.001). Patterns of mean female stature did not clearly support the hypothesis. Girls in the more affluent area were relatively tall and did not show significant variation. Results among less affluent girls showed significant contrasts, but not necessarily in the predicted direction.     

In memoriam: Maurice A. Bigelow

Abstract

Interracial children of white mothers and black fathers were compared to interracial children of black mothers and white fathers on growth rates during the first year of life. Results indicate that interracial children of white mothers gained less weight between birth and four months of age than did interracial children of black mothers or monoracial black or white children. By one year of age, catch‐up growth appears to have occurred, and there is little evidence for lasting effects of the growth retardation during the first four months of life.     

Big mothers invest more in daughters – reversed sex allocation in a weakly polygynous mammal

How mothers allocate resources to offspring is central to understanding life history strategies. High quality mothers are predicted to favour investment in sons over daughters when to do so increases inclusive fitness. This is the case in ungulates with polygynous mating systems, where reproductive success is more variable among males than females, but information is scarce on sex allocation in less polygynous species. Here, for the weakly dimorphic roe deer, we show that as maternal capacity to invest increases, mothers increase allocation to daughters more than to sons, so that relative allocation to daughters increases markedly with increasing maternal quality. This cannot be explained by a between sex difference in growth priority, hence we conclude that this is evidence for active maternal discrimination. Further, we demonstrate that condition differences between offspring persist to adulthood. For high quality mothers of weakly polygynous species, daughters may be more valuable than sons.     

A comparison of primiparous and multiparous mother-infant dyads inMacaca mulatta

The relationships of 42 rhesus monkey mother-infant dyads were examined to investigate the effects of the mothers' parity. Primiparous mothers were found to be younger, more excitable and less confident than the multiparous mothers. They also received more aggression from other adult females living in their social group and were more anxious about their infants, approaching and leaving them more frequently. The primiparous mothers protected their daughters more than the multiparous mothers and their daughters correspondingly spent more time in the ventro-ventral position and more time on the nipple. Their sons however spent less time in contact with their mothers than did the sons of the multiparous mothers. Although the primiparous mothers protected their daughters more than their sons, for the multiparous mothers the converse was true and sons received more maternal protection. It is suggested that the greater protectiveness of the multiparous mothers towards male infants may be a consequence of the interest siblings have in males, whereas the greater protectiveness of primiparous mothers to daughters may stem from their greater vulnerability to attacks from adult females. The importance of mother-mediated sibling influences may explain the lack of strong parity differences in previous studies.     

Social class and mobility in male adoptees and non-adoptees

414 adoptees were located in a population of 28,879 males born within a 4-year period from January 1, 1944 to December 31, 1947 whose mothers were officially resident in Copenhagen, Denmark when they gave birth. For all of these males, 2 social class ratings were obtained, based upon their occuppations at age 25-28 and 35-38. A single rating was obtained for their fathers, based upon occupation at the time of birth of the population males. In the case of adoptees, this rating wass obtained for both the biological and the adoptive fathers. The adoptees had, at both ages, an average social class not deviating from the population at large. Their biological fathers were, however, below average paternal social class and their adoptive fathers were above it. Positive correlations for social class were found between the adoptees, at both ages, and their biological and adoptive fathers. The social class of adoptees is less well predicted by that of their biological and adoptive fathers, even when these are taken jointly, than the social class of sons in the population is predicted by that of their fathers. Evidence from both the group means and the correlations suggests that the adoptees at age 35-38 came to resemble their biological fathers in social class more than they had done at age 25-28.