THE RELATION OF CLOSED BIRTH INTERVALS TO THE SEX OF THE PRECEDING CHILD AND THE SEXUAL ORIENTATION OF THE SUCCEEDING CHILD

1997 ◽  
Vol 29 (1) ◽  
pp. 111-118 ◽  
Author(s):  
RAY BLANCHARD ◽  
ANTHONY F. BOGAERT
Keyword(s):  
Sexual Orientation ◽  
Family Background ◽  
Control Variable ◽  
Female Child ◽  
Paternal Age ◽  
Homosexual Men ◽  
Sibship Size ◽  
Birth Intervals ◽  
Older Siblings ◽  
Older Sibling

The study investigated whether homosexual men are, on average, born a shorter time after their next-older siblings than are heterosexual men. Because of mixed evidence that birth intervals are longer after a male child, the sex of the next-older sibling was included as a control variable. The probands were 220 heterosexual and 183 homosexual men with at least one older sibling examined in Southern Ontario in 1994–95. These completed a self-administered, anonymous questionnaire concerning their family background and other biodemographic information. The results showed that birth interval was negatively correlated with sibship size, positively correlated with maternal age, and uncorrelated with paternal age. They also confirmed that birth intervals are longer after a male than after a female child. The mean birth intervals preceding heterosexual and homosexual males, however, were virtually identical, indicating that the association of short birth intervals with decreased sex hormone levels in cord blood is unrelated to the development of sexual orientation.

INFLUENCE OF SIBLINGS ON STUDENT SMOKING PATTERNS

PEDIATRICS ◽  
1963 ◽  
Vol 31 (4) ◽  
pp. 569-572
Author(s):  
Eva J. Salber ◽  
Brian MacMahon ◽  
Sarah V. Harrison
Keyword(s):  
Smoking Habits ◽  
Deterrent Effect ◽  
Public High School ◽  
Sibship Size ◽  
The Public ◽  
Smoking Patterns ◽  
Education Campaigns ◽  
To Come ◽  
Older Siblings ◽  
Older Sibling

Questionnaires on the smoking habits of school children, their parents, and their siblings were completed by 6,810 students (91%) in the public high school system of Newton, Massachusetts. Smokers tend to come from larger families than do nonsmokers. The larger sibship size results from smokers having more older siblings rather than more younger siblings. Frequency of smoking is much higher among children who are members of families in which there is an older sibling who smokes than among children of families where there are older siblings who do not smoke or where there are no older siblings. The risk of smoking to the index child does not vary with the sex of the older sibling to whom he is exposed. Older siblings who do not themselves smoke exert a slight deterrent effect on student smoking. These findings, together with earlier reports of the influence of parental smoking habits on the smoking patterns of children, are consistent with general concepts of the motivation of American (and perhaps all) teen-agers. They raise questions as to the advisability of health-education campaigns directed exclusively at children.

Birth spacing and infant and early childhood mortality in a high fertility area of Bangladesh: age-dependent and interactive effects

1995 ◽  
Vol 27 (4) ◽  
pp. 393-404 ◽  
Author(s):  
Nurul Alam
Keyword(s):  
Early Childhood ◽  
Birth Interval ◽  
Neonatal Period ◽  
Birth Spacing ◽  
Childhood Mortality ◽  
High Fertility ◽  
Birth Intervals ◽  
Risk Of Death ◽  
Older Siblings ◽  
Older Sibling

SummaryTo examine the effects of birth spacing on early childhood mortality, 3729 singleton births in 1983–84 were followed for 3 years in rural Bangladesh. Logistic regression analyses were used to assess whether the survival of older siblings modifies the effect of preceding birth intervals and to see if the effects of preceding and succeeding birth intervals are inter-related, controlling for the effects of sex of the child, mother's age and household economic status. With the exception of the neonatal period, birth spacing effects were highly significant. A preceding birth interval of <15 months was associated with a greater mortality risk in the post-neonatal period for children with an older sibling who survived infancy. However, a short preceding birth interval did not adversely affect post-neonatal mortality if the older sibling died in infancy. Neonatal and post-neonatal deaths were higher if older siblings had died in respective age intervals. A pregnancy interval of <12 months after childbirth raised the risk of death at ages 1–2 years considerably if the child was born after a short birth interval (<15 months). The results suggest that the high mortality risks of closely spaced children are due to sibling competition for parental resources.

Effects of Older Siblings on the Language Young Children Hear and Produce

1985 ◽  
Vol 50 (1) ◽  
pp. 84-99 ◽  
Author(s):  
Constance J. Wellen
Keyword(s):  
Young Children ◽  
The Other ◽  
Younger Child ◽  
Older Siblings ◽  
Older Sibling

Mothers told stories to their children, inserting 30 questions about each story under two conditions. In one situation, mothers were alone with their younger child, and in the other condition, an older sibling was also present. During the question-answer interactions, older siblings responded to 60%–65% of all mothers' questions before younger children had a chance to respond and provided direct answers to the questions in 57%–65% of those instances. Mothers responded by producing fewer rephrased questions, fewer questions providing hints and answers, fewer questions functioning as repetitions and expansions, and more directly repeated questions when the older sibling was present. The effect of older siblings' first responses also reduced by half the number of younger children's utterances. The younger children produced fewer noncontent and content answers and more imitated answers in the presence of the older sibling. It is concluded that the presence of older siblings may influence the language young children hear and produce.

scholarly journals Neural Correlates of Sexual Orientation in Heterosexual, Bisexual, and Homosexual Men

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Adam Safron ◽  
David Sylva ◽  
Victoria Klimaj ◽  
A. M. Rosenthal ◽  
Meng Li ◽  
...  
Keyword(s):  
Sexual Orientation ◽  
Neural Correlates ◽  
Homosexual Men

scholarly journals O Brother, Where Start Thou? Sibling Spillovers on College and Major Choice in Four Countries*

2021 ◽  
Author(s):  
Adam Altmejd ◽  
Andrés Barrios-Fernández ◽  
Marin Drlje ◽  
Joshua Goodman ◽  
Michael Hurwitz ◽  
...  
Keyword(s):  
Capital Investment ◽  
College Major ◽  
Spillover Effects ◽  
The United States ◽  
Major Choice ◽  
College Experiences ◽  
Multiplier Effects ◽  
Using Data ◽  
Older Siblings ◽  
Older Sibling

Abstract Family and social networks are widely believed to influence important life decisions, but causal identification of those effects is notoriously challenging. Using data from Chile, Croatia, Sweden, and the United States, we study within-family spillovers in college and major choice across a variety of national contexts. Exploiting college-specific admissions thresholds that directly affect older but not younger siblings’ college options, we show that in all four countries a meaningful portion of younger siblings follow their older sibling to the same college or college-major combination. Older siblings are followed regardless of whether their target and counterfactual options have large, small, or even negative differences in quality. Spillover effects disappear, however, if the older sibling drops out of college, suggesting that older siblings’ college experiences matter. That siblings influence important human capital investment decisions across such varied contexts suggests that our findings are not an artifact of particular institutional detail but a more generalizable description of human behavior. Causal links between the postsecondary paths of close peers may partly explain persistent college enrollment inequalities between social groups, and this suggests that interventions to improve college access may have multiplier effects.

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

2019 ◽  
Vol 17 (4) ◽  
pp. 147470491988070 ◽  
Author(s):  
Sarah Nila ◽  
Pierre-Andre Crochet ◽  
Julien Barthes ◽  
Puji Rianti ◽  
Berry Juliandi ◽  
...  
Keyword(s):  
Original Data ◽  
Heterosexual Men ◽  
Homosexual Men ◽  
Sibship Size ◽  
Male Homosexual ◽  
Heterosexual Women ◽  
Older Brothers ◽  
Fraternal Birth Order ◽  
Average Face ◽  
Cultural Effect

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.

Homosexuals who are Twins

1992 ◽  
Vol 160 (3) ◽  
pp. 407-409 ◽  
Author(s):  
Michael King ◽  
Elizabeth McDonald
Keyword(s):  
Sexual Orientation ◽  
Genetic Factors ◽  
Shared Knowledge ◽  
Homosexual Men ◽  
High Likelihood ◽  
Sexual Relations ◽  
Same Sex ◽  
Men And Women ◽  
Twin Research ◽  
High Level

Forty-six homosexual men and women who were twins took part in a study of their sexuality and that of their co-twin. Discordance for sexual orientation in the monozygotic pairs confirmed that genetic factors are insufficient explanation of the development of sexual orientation. There was a high level of shared knowledge of sexual orientation between members of twin pairs, and a relatively high likelihood of sexual relations occurring with same sex co-twins at some time, particularly in monozygotic pairs. The implications of these results for the study of the origins of sexual orientation and for twin research are discussed.

Teenage Sexual Orientation, Adult Openness, and Status Attainment in Gay Males

2002 ◽  
Vol 45 (2) ◽  
pp. 163-182 ◽  
Author(s):  
Donald C. Barrett ◽  
Lance M. Pollack ◽  
Mary L. Tilden
Keyword(s):  
Sexual Orientation ◽  
Educational Achievement ◽  
Family Background ◽  
Status Attainment ◽  
Health Study ◽  
Gay Males ◽  
Gay Male ◽  
The Status ◽  
Homosexual Activity ◽  
Early Decision

Research on the effects of sexual orientation on gay male status attainment has been hampered by the use of opportunistic samples and by the inability to control for family background and sexual orientation characteristics. This research uses data from the Urban Men's Health Study, a multicity probability sample, to examine the status attainment process among men who identify as gay or bisexual (N = 2,290). Logistic regression is used to measure the effects of teen sexual orientation and adult expression of sexual orientation on educational achievement and household income. Early decision that one is gay and early homosexual activity are related to reduced educational achievement. Teen sexual orientation and adult expression of sexual orientation are not directly related to income, though education was. These findings suggest that the costs of discrimination encountered early in life are an important component of the reduced status attainment of gay males.

scholarly journals Kisspeptin Expression in the Human Infundibular Nucleus in Relation to Sex, Gender Identity, and Sexual Orientation

2016 ◽  
Vol 101 (6) ◽  
pp. 2380-2389 ◽  
Author(s):  
Melanie Taziaux ◽  
Annemieke S. Staphorsius ◽  
Mohammad A. Ghatei ◽  
Stephen R. Bloom ◽  
Dick F. Swaab ◽  
...  
Keyword(s):  
Sexual Orientation ◽  
Sex Difference ◽  
Sexual Differentiation ◽  
Animal Studies ◽  
Outcome Measure ◽  
Sex Reversal ◽  
Heterosexual Men ◽  
Homosexual Men ◽  
Brain Sexual Differentiation ◽  
Male To Female

Abstract Context: Since the discovery of its central role in reproduction, our functional neuroanatomical knowledge of the hypothalamic kisspeptin system is predominantly based on animal studies. Although sex differences in kisspeptin expression have been shown in humans in adulthood, the developmental origin of this sex difference is unknown. Objectives: Our objectives were to determine the following: 1) when during development the sex difference in kisspeptin expression in the infundibular nucleus would emerge and 2) whether this sex difference is related to sexual orientation or transsexuality. Design and Setting: Postmortem hypothalamic tissues were collected by The Netherlands Brain Bank, and sections were stained for kisspeptin by immunohistochemistry. Patients: Hypothalami of 43 control subjects were categorized into three periods: infant/prepubertal (six girls, seven boys), adult (11 women, seven men), and elderly (six aged women, six aged men). Eight male-to-female (MTF) transsexuals, three HIV+ heterosexual men, and five HIV+ homosexual men were also analyzed. Main Outcome Measure: We estimated the total number of kisspeptin-immunoreactive neurons within the infundibular nucleus. Results: Quantitative analysis confirmed that the human infundibular kisspeptin system exhibits a female-dominant sex difference. The number of kisspeptin neurons is significantly greater in the infant/prepubertal and elderly periods compared with the adult period. Finally, in MTF transsexuals, but not homosexual men, a female-typical kisspeptin expression was observed. Conclusions: These findings suggest that infundibular kisspeptin neurons are sensitive to circulating sex steroid hormones throughout life and that the sex reversal observed in MTF transsexuals might reflect, at least partially, an atypical brain sexual differentiation.

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