Birth Order Data Research Articles

Siblings, shopping, and sustainability: Birth-order differences in green consumption.

Several studies have examined the role of birth order in shaping human personality, but fewer have tested this variable in relation to other pressing issues. We conducted a birth-order study on green consumption, which enabled us to detect a small-to-moderate effect size equivalent to r = 0.15 or d = 0.30 with sufficient statistical power (N = 335). To capture green consumption, participants indicated their tendency to express the value of environmental protection through purchases and consumption behaviors. Firstborns (vs. laterborns) consistently expressed lower concerns linked to environmental protection in their purchase patterns. While the effect size of this finding was small-to-moderate by conventional standards and in direct contrast to the findings from a recent article on the same topic, these results could still be informative to address challenges associated with climate change considering the number of individuals with siblings in the world and the ease with which birth-order data can be collected.

Evaluating indirect genetic effects of siblings using singletons.

Estimating effects of parental and sibling genotypes (indirect genetic effects) can provide insight into how the family environment influences phenotypic variation. There is growing molecular genetic evidence for effects of parental phenotypes on their offspring (e.g. parental educational attainment), but the extent to which siblings affect each other is currently unclear. Here we used data from samples of unrelated individuals, without (singletons) and with biological full-siblings (non-singletons), to investigate and estimate sibling effects. Indirect genetic effects of siblings increase (or decrease) the covariance between genetic variation and a phenotype. It follows that differences in genetic association estimates between singletons and non-singletons could indicate indirect genetic effects of siblings if there is no heterogeneity in other sources of genetic association between singletons and non-singletons. We used UK Biobank data to estimate polygenic score (PGS) associations for height, BMI and educational attainment in self-reported singletons (N = 50,143) and non-singletons (N = 328,549). The educational attainment PGS association estimate was 12% larger (95% C.I. 3%, 21%) in the non-singleton sample than in the singleton sample, but the height and BMI PGS associations were consistent. Birth order data suggested that the difference in educational attainment PGS associations was driven by individuals with older siblings rather than firstborns. The relationship between number of siblings and educational attainment PGS associations was non-linear; PGS associations were 24% smaller in individuals with 6 or more siblings compared to the rest of the sample (95% C.I. 11%, 38%). We estimate that a 1 SD increase in sibling educational attainment PGS corresponds to a 0.025 year increase in the index individual's years in schooling (95% C.I. 0.013, 0.036). Our results suggest that older siblings may influence the educational attainment of younger siblings, adding to the growing evidence that effects of the environment on phenotypic variation partially reflect social effects of germline genetic variation in relatives.

Birth order and the decline in college completion among the baby boom generation

We show that changes in birth order during the U.S. baby boom can explain a substantial share of the decline and recovery in college completion among cohorts born between 1946 and 1974. Combining birth order effects estimated using the Health and Retirement Survey and birth order data from Vital Statistics, we estimate that changes in birth order can explain about 20% of the decline in white male college completion rates among the 1946–60 cohorts, and about one third of the rebound among the 1960–74 cohorts.

Firstborns buy better for the greater good: Birth order differences in green consumption values

Despite multiple studies on the role of birth order in shaping human personality, marketing literature has largely neglected its role in shaping consumer behavior. We conducted a high-powered birth-order study on several consumption-related measures (Nmain analyses = 1358), which consistently enabled us to detect effect sizes even smaller than d = 0.20 with a power of 0.90. Participants filled out scales measuring susceptibility to normative interpersonal influence, the need for uniqueness, and the tendency to express the value of environmental protection through purchases and consumption behaviors. At a general level, we did not find any support for the notion that firstborns (vs. laterborns) are more susceptible to normative interpersonal influence or have a lower need for uniqueness. However, we found robust results regarding green consumption values, with firstborns valuing sustainability and proenvironmental consumption more than laterborns. Considering the number of consumers with siblings in the world and bearing in mind the ease with which birth-order data can be collected, these findings may have implications for activities aimed at mitigating climate change. However, the novel nature of our results calls for appropriate caution.

PO-064 Early birth order and increased risk of lymphoid cancers and allergies in lymphoid cancer families

IntroductionLymphoid cancers are a heterogeneous group of neoplasms that arise from immune cells. Familial clustering of lymphoid cancers support a genetic contribution to cancer predisposition. Infectious diseases and some immune disorders have been associated with lymphoid cancers. The hygiene hypothesis proposes that a lower infectious burden during early life inhibits the immune system from maturing optimally, and may lead to disorders of the immune system.Material and methodsWe characterised atopic conditions in lymphoid affected sibships of 182 families with a history of lymphoid cancers. Early life data was collected from telephone interviews and questionnaires from multiple family members. When available, medical records, pathology slides and tissue blocks were used to confirm the lymphoid cancer diagnosis. Lymphoid cancers were classified according to the InterLymph hierarchical classification (Turner, 2010). A chi-squared test for a linear trend in proportions was performed on birth order data for lymphoid affected sibships. This test was also performed on birth order and allergies in lymphoid affected sibships.Results and discussionsWithin 182 families, 301 sibships had 392 lymphoid affected and 927 unaffected siblings. We observed an inverse relationship between birth order and risk of cancer for all lymphoid cancers collectively (p<0.0001), and separately for multiple myeloma (p=0.0015), non-Hodgkin lymphoma (p<0.0001) and individual B-cell subtypes including chronic lymphocytic leukaemia (p=0.0124), follicular (p=0.0217) and marginal zone lymphoma (p=0.0169). We also observed an inverse relationship between birth order and risk of allergies (p=0.0284), for both environmental allergies (p=0.0465) and multiple allergies (p=0.0114) in lymphoid affected individuals.ConclusionEarly life exposures that are dependent on birth order may play a role in immune dysregulation and subsequent risk of multiple types of lymphoid cancers, as well as allergies. The familial nature of the cancers implies shared genetic and/or environmental factors. There is a need for further evaluation of lifestyle factors that may protect against lymphoid cancers even in the familial context.

Birth Order, Sibling Sex Ratio, Handedness, and Sexual Orientation of Male and Female Participants in a BBC Internet Research Project

This study investigated the relations among sexual orientation, fraternal birth order (number of older brothers), and hand-preference. The participants were 87,798 men and 71,981 women who took part in a Web-based research project sponsored by the British Broadcasting Corporation (BBC). The results yielded some evidence confirming prior findings that non-right-handedness is associated with homosexuality in men and women, that older brothers increase the odds of homosexuality in men, and that the effect of older brothers on sexual orientation is limited to right-handed men. The evidence was weaker than in previous studies, however, probably because the usual relations among the variables of interest were partially obscured by the effects of other factors. Thus, the homosexual men and women had higher rates of non-right-handedness than their heterosexual counterparts, but the strongest handedness finding for both sexes was a marked tendency for participants who described themselves as ambidextrous also to describe themselves as bisexual. The birth order data were strongly affected by a tendency for the male participants to report an excess of older sisters, and the female participants to report an excess of older brothers. Statistical analyses confirmed that this was an artifact of the parental stopping rule, "Continue having children until you have offspring of both sexes." In subsequent analyses, participants were divided into those who did and did not have younger siblings, on the grounds that the data of the former would be less contaminated by the stopping rule. In the former subsample, the right-handed homo/bisexual males showed the typical high ratio of older brothers to older sisters, whereas the non-right-handed homo/bisexual males did not.

Edad materna y defectos del tubo neural: evidencia para un efecto mayor en espina bífida que anencefalia

Recent evidence from birth order data suggest that maternal factors can differently influence anencephaly and spina bifida.To study the influence of maternal age on the risk for neural tube defects.A meta-analysis of published data on neural tube defects (NTDs) was carried out to determine whether there is an increased risk to have a child with NTDs for younger and older mothers and if this risk differs depending on the type of NTD. All data available with information regarding the frequency of live births and NTDs cases by maternal age (five- or ten-year intervals) were included in the analysis. Effect sizes calculations were performed.The analysis supports the hypothesis that there is an increased risk of having an offspring with NTDs for mothers 40 years of age or older. However, this effect is stronger for spina bifida than for anencephaly. There is also evidence that mothers 19 years old or younger have a higher risk for having a child with spina bifida.Maternal age influences the risk of having an offspring with neural tube defects.

Top Gun Fighter Pilots Provide Clues to More Effective Database Marketing Segmentation: The Impact of Birth Order

A major issue in the construction of a database is what data to collect about customers in order to maximise targeting efficiency. The paper examines a variable hitherto neglected by marketers but which has been shown in psychology literature to have significant influence on a wide variety of adult behaviour, including fighter pilot effectiveness. There is evidence that birth order shapes personality, in particular what Sulloway refers to as the "Big Five" personality dimensions. This paper reviews the psychology literature, discusses the potential implications for marketers, in particular database marketing, and reports on two studies (including a nationally representative sample of 967 adults) that support the hypothesis that first-borns show a greater need than later-borns to talk to others before and/or after a high involvement purchase. The implications for methods of direct marketing communication and communication content are noted. The simplicity of collecting birth order data, coupled with the ability of neural networks software to process many customer variables, e.g. demographic and transactional, in order to optimise targeting efficiency, makes ordinal birth position a prime candidate for inclusion on consumer databases.

The relation of birth order to sexual orientation in men and women.

Homosexual men have a higher mean birth order than do heterosexual men, primarily because they have a greater number of older brothers. The purpose of this study was to determine whether the same difference occurs in homosexual vs heterosexual women. The probands were 964 homosexual and heterosexual, male and female volunteers, from whom birth order data were collected with self-administered questionnaires. The homosexual men had more older brothers than the heterosexual men, but they did not have more older sisters, younger brothers, or younger sisters. The homosexual women did not differ from the heterosexual women with regard to any class of sibling. These results are consistent with the hypothesis that the high birth order of homosexual men reflects the progressive immunization of certain mothers to H-Y antigen by succeeding male fetuses, and the increasing effects of H-Y antibodies on sexual differentiation of the brain in succeeding male fetuses.

Age at first establishment of chronic hepatitis B virus infection and hepatocellular carcinoma risk. A birth order study.

It is frequently assumed that the risk of hepatocellular carcinoma related to hepatitis B virus is higher when chronic hepatitis B virus infection is acquired early in life. This hypothesis has never been directly evaluated. However, firstborn and secondborn children are exposed to common infections after their school enrollment, whereas laterborn children are exposed much earlier, through their older siblings. The authors analyzed sibship size and birth order data from a large case-control study of patients admitted to Athens, Greece, hospitals between April 1976 and October 1984. The analyses included 185 patients with hepatocellular carcinoma, 35 patients with metastatic liver cancer, and 432 other hospital controls. There was a tendency for cases of hepatocellular carcinoma to concentrate at higher birth orders. When the analysis was restricted to cases and controls who were positive for hepatitis B surface antigen, this tendency was even more notable. These results are compatible with the hypothesis that establishment of chronic hepatitis B virus infection at an early age increases the risk of hepatocellular carcinoma substantially more than does chronic infection with this virus established at a later age.

Fertility projection based on birth order data – A Swedish approach

"The decreasing fertility rates in Sweden during the 1970s can be explained as postponement of childbearing. An increasingly larger part of each generation has chosen to bear children at a late age, after education and some years of occupational work. As a consequence, the yearly age-specific rates will, in years to come, change systematically towards relatively high rates for women in the second half of the fertile period; changes which are important in population projections. To predict the future rates a model based on birth order data and assumptions about the final family size is used. The model and its application in the 1989 projection of the Swedish population is discussed in the paper. Alternative projections and the assumptions behind the alternatives are specified."

Choice of ascertainment model II. Discrimination between multi-proband models by means of birth order data.

Probability models have been developed for family data, where each family has been selected or ascertained through a group of m probands, where m is a known parameter, not a random variable. The birth orders of the probands among the affected children are reported for each family. It is demonstrated that this information is sufficient for choice of ascertainment model. The conditional probability that an ascertained family with s children has r affected ones, depends, in addition to the segregation parameter, on the birth order of the youngest proband only. By means of the joint distribution of the birth orders of the other probands, it can be demonstrated if the ascertainment takes place through affected children near to or distant from each other in relative birth orders. Statistical methods have been developed for cases with two and cases with m probands.

Choice of ascertainment model I. Discrimination between single-proband models by means of birth order data.

A statistical method for choosing between ascertainment models for human family data has been constructed. The families are assumed to have been ascertained through a single proband each and the birth number of the proband among the affected children is recorded. If the proband is the eldest affected child in each family the so-called complete ascertainment model has to be used. If each affected child has the same probability of being the proband, the so-called single ascertainment model should be used. In intermediate cases a third ascertainment model should be used.

Birth Order, Anxiety, Affiliation and the Purchase of Life Insurance

This paper is a preliminary investigation into the role of anxiety in insurance purchasing decisions. Because the psychological literature with respect to birth order provides indications of differential anxiety levels and affiliative behavior under stressful conditions, the study examines the role of birth order in relating anxiety to insurance purchasing decisions. It was hypothesized that first and only children would purchase more life insurance, total and individual, than would later borns. Samples, including demographic as well as insurance purchasing and birth order data, were drawn from two student populations at opposite ends of the country. The data were subjected to multiple regression analysis and support for the hypotheses was indicated by only one of the samples. After analysis of the findings, suggestions for further research are provided. Risk reduction is said to be the basic product or service provided by insurers. Among the more popular definitions of risk are those involving uncertainty of loss. Through the payment of a premium, the insured reduces his uncertainty regarding the possibility of an economic loss. Pfeffer (15), makes this uncertainty

Pleasing and interesting visual complexity: support for Berlyne.

Berlyne has stated that there are two kinds of exploratory behavior, specific and diversive, and has cited data relating to “pleasingness” and “interestingness” of complex visual patterns in support of his position. In order to test Berlyne's views, 28 Ss rank ordered nine polygons, of varying degrees of complexity, in terms of “pleasingness” and “interestingness.” Highly complex polygons were found to be more interesting, in support of Berlyne. No significant differences emerged for the “pleasingness” category. Birth order data showed a nonsignificant tendency for first borns to choose less complex polygons as more pleasing than higher complexity shapes.

Visual acuity, birth order, achievement versus affiliation, and other Edwards personal preference schedule scores

Refractive errors, EPPS scores, and birth-order data were obtained form 109 male students. Ametropes (near-sighted and far-sighted persons) (i) scored higher on Affiliation and Nurturance, and lower on Achievement, (ii) achieved “via” Dominance, Endurance, or Order and (iii) tended to be first borns. “Emmetropes” (normal-sighted persons), redefined to include mild myopes (near-sighted persons), (i) scored higher on Achievement, and lower on Affiliation and Nurturance (ii) achieved “via” Independence and (iii) tended to be later borns. Mild myopes, in contrast to more advanced myopes, scored higher on Intraception. The birth-order findings were consistent with speculation concerning child-rearing practices in the development of ametropia. The finding that the two types of ametrope score similarly on some variables was inconsistent with the viewpoint that myopes and hyperopes are polar opposites.

The Relationship of Birth Order and Fraternal Position to Incidence of Insanity

This study is an attempt to discover the relationship between the position of a child in his sibship and the development of certain personality traits. Some abnormal behavior traits, when exhibited by adults, result in the diagnosis of insanity. Hence, a statistical analysis of the birth order and fraternity position of individuals committed as insane should reveal a relationship between these two factors, if such a relationship exists. It is very difficult to secure a sufficient number of complete and unequivocal records of the insane so far as birth-order data are concerned. Using certain methodological rules, however, data on about 1,200 cases are obtained. Analysis of these records leads to the conclusion that among the insane there is no very reliable or significant relation between incidence of insanity and position of the patient in his sibship when the sibship is larger than two. In fraternities of two, however, the insane individual is much more frequently the elder than the younger.