An immunoreactive theory of selective male affliction

Gualtieri, C. Thomas; Hicks, Richard E.

doi:10.1017/s0140525x00001023

Cited by 223 publications

(79 citation statements)

References 292 publications

(188 reference statements)

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“…This explanation is partly based on the idea that a woman's immune system would appear to be capable of remembering the number of male fetuses she has previously carried and of progressively altering its response to the next fetus according to the current tally of preceding males. A mother's body may have a memory for male (but not female) fetuses because she herself is female, and thus, her immune system may interpret and remember male (but not female) fetuses as foreign (21). If this immune theory were correct, then the link between the mother's immune reaction and the child's future sexual orientation would probably be some effect of maternal anti-male antibodies on the sexual differentiation of the brain.…”

Section: Resultsmentioning

confidence: 99%

Biological versus nonbiological older brothers and men’s sexual orientation

Bogaert

2006

Proc. Natl. Acad. Sci. U.S.A.

211

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The most consistent biodemographic correlate of sexual orientation in men is the number of older brothers (fraternal birth order). The mechanism underlying this effect remains unknown. In this article, I provide a direct test pitting prenatal against postnatal (e.g., social͞rearing) mechanisms. Four samples of homosexual and heterosexual men (total n ‫؍‬ 944), including one sample of men raised in nonbiological and blended families (e.g., raised with halfor step-siblings or as adoptees) were studied. Only biological older brothers, and not any other sibling characteristic, including nonbiological older brothers, predicted men's sexual orientation, regardless of the amount of time reared with these siblings. These results strongly suggest a prenatal origin to the fraternal birthorder effect.immune ͉ sexuality R ecent research has provided evidence that genetic and prenatal factors may influence sexual orientation development (1-7). In this article, I demonstrate that the number of biological older brothers, including those not reared with the participant (but not the number of nonbiological older brothers), increases the probability of homosexuality in men. These results provide evidence that a prenatal mechanism(s), and not social and͞or rearing factors, affects men's sexual orientation development.The most consistent biodemographic correlate of sexual orientation in men is the number of older brothers, originally observed by Blanchard and Bogaert (8) in a Canadian sample in the 1990s but since then found in samples from different eras and from different countries, both by us and independent investigators (2, 7, 9-12). Evidence does not exist that sibling characteristics reliably correlate with women's sexual orientation (13,14). Both childhood social͞rearing (13, 15, 16) and prenatal (8, 13) mechanisms have been advanced to account for the older brother (''fraternal birth-order'') effect in men, but a direct test pitting prenatal versus postnatal (e.g., social͞rearing) mechanisms is lacking. Such a test is possible when information on both biological and nonbiological siblings, along with sexual orientation, is included in the research design.Four samples of homosexual and heterosexual men (total n ϭ 944) reporting on their parental and sibling characteristics (i.e., biological and nonbiological siblings) were examined to test this issue. Three samples were archival and contained men with (largely) biologically intact families. These samples contained information on all siblings (both biological and nonbiological) with whom the participant was reared. The fourth sample was recruited specifically to test the research issue investigated in this article and contained men with nonbiological or blended families (e.g., raised with half-or step-siblings or as adoptees). This final sample also contained information on the amount of time the participants were reared with each sibling, along with information on any biological siblings with whom they were never reared.If rearing or social factors associated with older m...

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Section: Resultsmentioning

confidence: 99%

Biological versus nonbiological older brothers and men’s sexual orientation

Bogaert

2006

Proc. Natl. Acad. Sci. U.S.A.

211

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“…Importantly, the prevalence of such anomalies also appears to be greater in healthy males, compared to healthy females (Akabaliev and Sivkov, 2003). Male fetuses are known to be more susceptible to intrauterine insults than females (Gualtieri and Hicks, 1985). It has also been proposed that male schizophrenia patients are more likely to exhibit a congenital variant of schizophrenia, reflecting abnormal prenatal development (Castle and Murray, 1985;Murray et al, 1992).…”

Section: Discussionmentioning

confidence: 99%

Reduced posterior nasal cavity volume: A gender-specific neurodevelopmental abnormality in schizophrenia

Turetsky

Glass

Abbazia

et al. 2007

Schizophrenia Research

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Objective-We previously reported that men with schizophrenia had reduced volumes of the posterior nasal cavity bilaterally. Since the nasal cavities develop in conjunction with both the palate and ventral forebrain, this could represent a simple marker of embryological dysmorphogenesis contributing to schizophrenia. The current study expands on this finding by examining a larger sample of both male and female patients and unaffected 1 st -degree relatives, to determine the gender distribution of this abnormality and the extent to which it may be genetically mediated.Method-A measurement of nasal volume and geometry was acquired by acoustic rhinometry for 85 schizophrenia patients, 25 unaffected first-degree relatives of schizophrenia probands and 66 healthy comparison subjects.Results-Male patients had smaller posterior nasal volumes than both male control subjects and male relatives. However, female patients did not differ from either female controls or female family members. Unaffected first-degree relatives did not differ from same-sex control subjects. These findings persisted after covarying for height and smoking history, and were unrelated to clinical symptomatology or antipsychotic medication usage.Conclusion-Posterior nasal cavity volume decrement appears to be a specific developmental craniofacial abnormality that may reflect an early disruption in embryological development in males with schizophrenia. Although further study is needed, this may be a marker of a "second hit" that distinguishes genetically vulnerable men who go on to develop the illness from those who do not.

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“…One hypothesis suggests an effect of maternal antibody attack on the fetal brain: Maternal antibody levels tend to increase by higher birth orders in a suggested mechanism parallel to rhesus incompatibility and erythroblastosis (6). It has been shown that children of mothers with autoimmune disease have an increased risk of learning disabilities [for example, (7)], but there are no empirical data to support immunoreactivity in explaining the birth order effect.…”

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confidence: 99%

Explaining the Relation Between Birth Order and Intelligence

Kristensen

Bjérkedal

2007

Science

203

129

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T he interest in the relation between birth order and intelligence dates back to Sir Francis Galton's English Men of Science (1). Galton found more firstborn sons in prominent positions than what he attributed to chance. This was the start of numerous studies; one of the most influential was a Science publication in 1973 showing a negative association between birth order and intelligence in young Dutch men (2). Since then, sociologists, psychologists, and demographers have proposed several explanatory models (3). The most influential models have emphasized explanations relating to interactions within the family and favorable conditions for intellectual stimulation for lowbirth-order children.Several researchers have claimed that the relation between birth order and intelligence is false, confounded by factors relating to family size: Families with low-intelligence children tend to be large, and the relation with birth order is an artifact when comparisons between families are made (3). This explanation would not produce birth order effects between siblings. Thus, the demonstration of small but notable birth order effects on intelligence quotient (IQ) in large studies examining relations within families (4, 5) contradicts the idea that artifact is the full explanation.A third model claims that the relation is explained by prenatal or gestational factors. One hypothesis suggests an effect of maternal antibody attack on the fetal brain: Maternal antibody levels tend to increase by higher birth orders in a suggested mechanism parallel to rhesus incompatibility and erythroblastosis (6). It has been shown that children of mothers with autoimmune disease have an increased risk of learning disabilities [for example, (7)], but there are no empirical data to support immunoreactivity in explaining the birth order effect.Some children have different social and biological ranks in the family. One example is children who grow up in families with deceased elder siblings. A social interaction effect within the family would result in higher scores for a secondborn who had lost an elder sibling than for subjects ranked second both socially and biologically. On the other hand, if the birth order effect was gestational, secondborn children who are raised as the eldest would have IQ scores equal to those of other secondborn children.We have data on birth order, vital status of elder siblings, and IQ scores among male Norwegian conscripts (8). This gave us an opportunity to test the family interaction and the gestational explanations. We anticipated that men who had a biological rank different from the social rank would score better than males of similar birth order who had not experienced the early loss of elder siblings if the social interaction hypothesis was right, whereas similar scores would support the gestational hypothesis. Because children from families with an adverse reproductive history had a less-advantageous distribution on a number of factors associated with low IQ (8), we considered it important to adjust for those f...

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An immunoreactive theory of selective male affliction

Cited by 223 publications

References 292 publications

Biological versus nonbiological older brothers and men’s sexual orientation

Biological versus nonbiological older brothers and men’s sexual orientation

Reduced posterior nasal cavity volume: A gender-specific neurodevelopmental abnormality in schizophrenia

Explaining the Relation Between Birth Order and Intelligence

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