The Fraternal Birth-Order Effect as Statistical Artefact: Convergent Evidence from Probability Calculus, Simulated Data, and Multiverse Meta- Analysis

For a quarter of a century researchers investigating the origins of sexual orientation have largely ascribed to the fraternal birth order effect (FBOE) as a fact, holding that older brothers increase the odds of homosexual orientation among men through an immunoreactivity process. Here, we triangulate the empirical foundations of the FBOE from three distinct, informative perspectives: First, drawing on basic probability calculus, we deduce mathematically that the body of statistical evidence of the FBOE rests on the false assumptions that effects of family size should be controlled for and that this could be achieved through the use of ratio variables. Second, using a data-simulation approach, we demonstrate that by using ratio variables, researchers are bound to falsely declare corroborating evidence of an excess of older brothers at a rate of up to 100%, and that valid approaches attempting to quantify a potential excess of older brothers among homosexual men must control for the confounding effects of the number of older siblings. And third, we re-examine the empirical evidence of the FBOE by using a novel specification-curve and multiverse approach to meta-analysis. This yielded highly inconsistent and moreover similarly-sized effects across 64 male and 17 female samples (N = 2,778,998), compatible with an excess as well as with a lack of older brothers in both groups, thus, suggesting that almost no variation in the number of older brothers in men is attributable to sexual orientation.

Cytosolic Phosphoenolpyruvate Carboxykinase Deficiency: Cause of Hypoglycemia-Induced Seizure and Death

Cytosolic phosphoenolpyruvate carboxykinase (PEPCK) deficiency (MIM 261680, EC 4.1.1.32, encoded by PCK1) is a rare disorder of gluconeogenesis presenting with recurrent hypoglycemia, hepatic dysfunction, and lactic acidosis. We report on a previously healthy 3-year-old boy who was initially admitted under the suspicion of a febrile seizure during an upper airway infection. Diagnostic workup revealed hypoglycemia as well as a cerebral edema and ruled out an infection. After a complicated course with difficult to treat symptomatic seizures, the child died on the 5th day of admission due to progressive cerebral edema. The metabolic screening showed elevated urinary lactate and Krebs cycle intermediates in line with a primary or secondary energy deficit. Due to the unclear and fatal course, trio exome sequencing was initiated postmortem (“molecular autopsy”) and revealed the diagnosis of cytosolic PEPCK deficiency based on the compound heterozygosity of a known pathogenic (c.925G > A, p.(Gly309Arg)) and a previously unreported (c.724G > A, p.(Gly242Arg)) variant in PCK1 (NM_002591.3). Sanger sequencing ruled out the disease and carrier status in three older brothers. Molecular autopsy was performed due to the unclear and fatal course. The diagnosis of a cytosolic PEPCK deficiency not only helped the family to deal with the grief, but especially took away the fear that the siblings could be affected by an unknown disease in the same manner. In addition, this case increases the genetic and phenotypic spectrum of cytosolic PEPCK deficiency.

Influencia familiar en la elección de carreras STEM (Ciencia, tecnología, ingeniería y matemáticas) en estudiantes de bachillerato

La sociedad experimenta cambios científicos y tecnológicos que están obligando a las economías a centrar su atención en la formación de capital humano con un perfil en ciencia, tecnología, ingeniería y matemáticas (STEM por sus siglas en inglés). Elegir una carrera es una decisión de tipo individual y familiar, este artículo tiene como objetivo conocer la influencia de la familia (madre o tutora, padre o tutor y hermanos) en la elección de carreras STEM en estudiantes de segundo y sexto semestre de bachillerato. Se entrevistó a 1 mil 759 estudiantes de seis bachilleratos distintos, a través de un muestreo no probabilístico, por cuotas. Los resultados muestran que la madre o tutora es la figura que más influye en la elección de una carrera STEM en comparación con el padre o tutor. Se pensó que los hermanos podrían tener un efecto mayor en los estudiantes, no obstante, los resultados muestran que no es significativo que tengan o no hermanos y que estos puedan influir en la elección de carrera. Sin embargo, es necesario profundizar más en el estudio de los hermanos mayores que egresan de carreras STEM y el efecto que esto tiene en la elección de los hermanos menores, aspecto que no se abordó en la investigación. El estudio no profundizo en variables como: el tipo de carrera y el rol laboral que desempeñan los padres y si está o no relacionado con las áreas STEM. Se concluye que las familias deben realizar actividades no formales que ayuden a despertar el interés en la ciencia y aumentar su capital cultural desde edades tempranas. Society experiences scientific and technological changes that are forcing economies to focus their attention on the development of human capital with a profile in science, technology, engineering and mathematics (STEM). This article aims to demonstrate the influence of the family (mother or guardian father or guardian and siblings) on the choice of STEM careers in high school students during their second and sixth semester, since choosing a career is an individual and family decision. A total of 1,759 students from six different high schools were interviewed, through a non-probabilistic sampling, by quotas. The results show that the mother or guardian is the figure that most influences the choice of a STEM career compared to the father or guardian. It was thought that siblings could have a greater effect on students, however, the results show that it is not significant that they have siblings or that siblings can influence their choice. However, it is necessary to go deeper into the study of older brothers who graduate from STEM degrees and the effect this has on the younger brother’s election, an aspect that was not addressed in the investigation. The study did not delve into variables such as the type of career and the labor role played by parents and whether or not it is related to STEM areas. In conclusion, families must carry out non-formal activities that help awaken interest in science and increase their cultural capital from an early age.

Parent-Reports of Sex-Typed Play Preference in Preschool Children: Relationships to 2D:4D Digit Ratio and Older Siblings’ Sex

Sex-typed play behavior shows large sex differences and seems to be affected by prenatal sex hormones. For example, a smaller, more male-typical ratio between the second and fourth digit length (2D:4D), a proposed marker for prenatal testosterone exposure, has been shown to be related to sex-typed play preference in childhood. Nevertheless, it is still being debated whether 2D:4D displays a stable sex difference throughout childhood, as there are few longitudinal studies. In the present study, children’s 2D:4D was measured on both hands on four occasions from early infancy to early childhood (T1: 5 months, T2: 9 months, T3: 20 months, and T4: 40 months) providing the rare possibility to test the temporal stability of the sex difference. Parents completed the Preschool Activities Inventory at T4 and reported on the number of older brothers and sisters as a measure for socialization influences. Parents described boys as playing more masculine and less feminine than girls. Boys had smaller 2D:4D than girls at all measurements (T1–T4) and on both hands (right/left). Nevertheless, 2D:4D increased significantly from T3 to T4 in both sexes. Girls, but not boys, who were described as playing more masculine and less feminine had more masculine 2D:4D ratios at T1–T4 on both hands (except for right 2D:4D at T2 and T3) and had more older brothers and fewer older sisters. These data underline the stability of the sex difference in 2D:4D and show the importance of both biological and social influences on sex-typed play behavior.

A method yielding comparable estimates of the fraternal birth order and female fecundity effects in male homosexuality

The fraternal birth order effect (FBOE) is the finding that older brothers increase the probability of homosexuality in later-born males, and the female fecundity effect (FFE) is the finding that the mothers of homosexual males produce more offspring than the mothers of heterosexual males. In a recent paper, Khovanova proposed a novel method for computing independent estimates of these effects on the same samples and expressing the magnitude and direction of the effects in the same metric. In her procedure, only families with one or two sons are examined, and daughters are ignored. The present study investigated the performance of Khovanova's method using archived data from 10 studies, comprising 14 samples totalling 5390 homosexual and heterosexual subjects. The effect estimate for the FBOE showed that an increase from zero older brothers to one older brother is associated with a 38% increase in the odds of homosexuality. By contrast, the effect estimate for the FFE showed that the increase from zero younger brothers to one younger brother is not associated with any increase in the odds of homosexuality. The former result supports the maternal immune hypothesis of male homosexuality; the latter result does not support the balancing selection hypothesis.

Male Homosexual Preference: Femininity and the Older Brother Effect in Indonesia

Male homosexual preference (MHP) is an evolutionary enigma because it is partially heritable and imposes a fertility cost. In occidental societies, homosexual men are feminized at various levels and they have more older brothers than heterosexual men. To evaluate whether femininity and the fraternal birth order (FBO) effect are universal features of MHP or not, we collected original data from homosexual men, heterosexual men, and heterosexual women from Java (Indonesia). Facial photographs were used to test whether homosexual faces are feminized when compared with heterosexual ones. We found that faces manipulated to resemble the average face of homosexual men are perceived as facially feminized, suggesting that homosexual men are facially feminized compared to heterosexual men, although a higher facial femininity was not captured by morphological analyses. Then, family data were used to detect differences in siblings’ composition between homosexuals and heterosexuals. Homosexual men displayed a higher number of older brothers than heterosexual men, even when sibship size was controlled for, suggesting that the FBO effect exists in Indonesian populations. Independent of sexual orientation, men with older brothers seem more feminized than those without older brothers, consistent with the immune origin of the FBO effect. In conclusion, MHP in Indonesia is partially feminized and they have more older brothers. Such features are also associated with MHP in other cultural contexts, suggesting a cross-cultural effect of men homosexual preference. An evolutionary explanation is available for the feminizing effect, although the FBO effect remains unexplained even if proximal mechanisms start to be identified.

One piece of the matrilineal puzzle: the socioecology of maternal uncle investment

Maternal uncle relationships in which men invest resources (usually in the form of inheritance of material wealth) into their sisters' children are characteristic of matrilineal systems and hypothesized to arise under certain socioecological circumstances, but little research has systematically investigated conditions that are associated with this type of investment. We quantify relationships between household-level socioeconomic variables and different types of maternal uncle investment (direct care and indirect resource investment) within a bilateral, semi-nomadic population. Shodagor people of Bangladesh allow us to consider matrilineal behaviours in an evolutionary framework owing to their flexible social structure in which 39% of families receive some investment from a maternal uncle. Variables associated with direct maternal uncle care reflect the significance of maintaining consistent residence throughout the year and an increased need for childcare in families residing on boats versus those living on the land. Informative predictors of indirect investment indicate that a mother's birth history corresponds with more tangible contributions such as food and clothing. These results identify household-level variables specific to direct versus indirect maternal uncle investment, whereas having more older brothers or being firstborn increased the odds of a mother receiving any investment from brothers at all. Exploring these social and ecological associations in a bilateral, relatively flexible population unveils household circumstances that may lead to the development of female-biased kinship. This article is part of the theme issue ‘The evolution of female-biased kinship in humans and other mammals'.

The effect of siblings on language development as a function of age difference and sex

The number of older siblings a child has is negatively correlated with their verbal skills, perhaps due to competition for parents’ attention. The current study examined the role of siblings’ sex and age gap as moderating factors, reasoning that they affect older siblings’ tendency to compensate for reduced parental attention. We hypothesized that children with an older sister, especially with a large age gap, have better language abilities than those with older brothers. We reanalyzed data from the EDEN cohort (N = 1,154) and found that children with an older sister had better language skills than those with an older brother. Contrary to predictions, the age gap between siblings was not associated with language skills, and did not interact with sex. Results suggest the negative effect of older siblings on language development may be entirely due to older brothers, and invite further research on the mechanisms involved in this effect.

MEDIA BONEKA TANGAN DAPAT MENINGKATKAN KETERAMPILAN MENYIMAK ANAK USIA 5-6 TAHUN DENGAN METODE BERCERITA

One from of ability to tell stories is the listening process.in general, older brothers still have difficulty listening to and unerstanding the stories that the teacher conveyed, one of conditions is the influence of the teacher’s low creativity in determining the medium of learning to tell childeren. On the other hand children are still less focused and often talk to themselves with their friends so that children do not concentrate and listen to the explanation from the teacher, this happens to the child and during the learning process. This phenomenon is a problem that needs to be found as an alternative solution. One methode that can be used is the storrytelling methode using hand puppet media. This study used a classroom action research methode which numbered 12 children. The results obtained from 12 children are significant, no children are undeveloped, if the value is obtained, it is 0 percent, 1 child begins to develop, if the value is obtained, it is8%, 4 children have developed as expected or if the value is obtained, it is 32%, and 7 children develop very well or if the value is obtained, its is 60%. From the percentage accumulated there was an average increase of 33%. According to the results of improvement in each cycle, the use of hand puppet media on story telling techniques can influence the listening skills of group B children in this kindergarten. From tehe data obtained it can be concluded that the media of hand puppets can improve the listening skill of children.Keywords: Listening Skill, tell stories, Hand Puppet