A linkage between DNA markers on the X chromosome and male sexual orientation

Eugenics and individual phenotypic variation: to what extent is biology a predictive science?

Eugenics, in whatever form it may be articulated, is based on the idea that phenotypic characteristics of particular individuals can be predicted in advance. This paper argues that biology's capacity to predict many of the characteristics exhibited by an individual, especially behavioral or cognitive attributes, will always be very limited. This stems from intrinsic limitations to the methodology for relating genotypes to phenotypes, and from the nature of developmental processes which intervene between genotypes and phenotypes. While genetic studies may generate valid population predictions for conditions which impact human health, neither genetics nor developmental biology are likely to generate useful individual predictions about variation in non-disease-related human behavioral and cognitive phenotypes in the foreseeable future.

APA, science, and the Defense of Marriage Act

This paper uses the APA position on the Defense of Marriage Act to demonstrate that APA's advocacy policy regarding homosexual marriage is not based on science. It shows that the politics of advocacy have led a purportedly scientific organization to misinterpret, overgeneralize, and distort the results of research and to ignore the original purpose of the organization.

Immediate effects of written material on attitudes toward homosexuality

This study examined whether attitudes toward homosexuals were affected by educational material containing information about the biological determinants of sexual orientation. This study utilized a normed two-alternative inventory on which participants were asked to rate matched items on a 5-point scale. In the first session participants completed one version involving interactions with homosexual individuals. One week later, participants, randomly assigned to one of three groups, filled out the matched alternative form after reading a summary that presented either a biological or environmental basis for homosexuality or an unrelated article. Analysis confirmed previous research that the 40 men had more negative attitudes toward homosexuals than the 40 women but that different types of explanations for homosexuality had no over-all influence on attitudes. More importantly, an item analysis extended our previous understanding of sex differences in that physical proximity to the homosexual individual was the strongest factor associated with attitude change.

Investigation and management of patients at high risk of developing cancer

Recent developments in cancer genetics have revealed genes that render individuals susceptible to cancer. These families have a unique set of new problems and benefits that must be thought through for the potential good to be accrued from these discoveries. Individual patients seek early diagnosis and prevention strategies that challenge the limits of current knowledge. Some available methods have not yet been evaluated. There is a need for the evidence to support plans of care, and consistency is required from one centre to the next in the advice given. These familial cancers are often different from the more common sporadic cases, and so traditional treatments need to be tested again in the context of the new genetic knowledge. Three groups of cancers, breast, ovary and colon, have been used to illustrate the issues surrounding these high risk families, their investigation and care. In applying new strategies to these patients, ethical issues arise that are new to the medical world, and must be considered by the lay public. It is up to the medical profession, patients and society to use this knowledge to give benefit to a vulnerable group, and not to give unaffordable hopes and unnecessary anxieties.

Gender identity disorder: a review of the past 10 years

OBJECTIVE

To review the clinically relevant literature on gender identity disorder (GID) in children and adolescents over the past 10 years.

METHOD

All literature referring to gender identity and children or adolescents from 1985 on was reviewed.

RESULTS

Changes in the DSM-IV nomenclature include (1) adoption of the single diagnosis of GID to apply to children, adolescents, and adults; (2) changes in the format of the criteria; and (3) placement in the section "Sexual and Gender Identity Disorders." Rates of associated psychopathology in children with GID are comparable with those in children with other psychiatric disorders, particularly disorders that are internalizing in form. Biological and psychosocial factors thought to be relevant in the development of GID are reviewed.

CONCLUSIONS

Research is required to elucidate the complicated interaction between biological and psychosocial factors in the development of GID and to evaluate treatment efficacy.

Ethical implications of scientific research on the causes of sexual orientation

In this article, we evaluate the status of current biological research into sexual orientation and examine the relevance of such research on the legal and social status of gay men and lesbians. We begin with a review of hormonal neuroanatomical and genetic studies of sexual orientation. We argue that the scientific study of sexual orientation is, at best, still in its infancy. We turn then to the ethical and social implications of this research. We argue that even if scientists could explain how sexual orientation develops, no significant ethical conclusions would follow. Further, we suggest that the current emphasis on finding a biological basis for sexual orientation is potentially harmful to lesbians, gay men and other sexual minorities in various ways (although perhaps it is in some ways potentially helpful as well).

Lesbian motherhood: the impact on child development and family functioning

The wide variety of lesbian families who became visible during the past 20 years gave rise to important practical and theoretical questions. Up to now society has treated lesbian mothers differently with regard to a number of child-issues. In the past, divorcing lesbian mothers were often denied child custody because of their sexual orientation and the majority of fertility centers still refuse lesbian couples in their donor insemination programs. The present article reviews whether there is any theoretical and empirical evidence for the most widespread assumptions on which such decisions have been based. A number of psychological theories, such as psychoanalytic theory, social and cognitive learning theory and attachment theory are discussed with regard to the two most salient features of lesbian families; the absence of a father and the homosexual orientation of the mother. Meanwhile, there is a growing body of empirical research investigating a variety of aspects of child development, such as gender development, emotional/behavioral adjustment and social competence. Most of these studies involved children of divorced lesbian mothers who spent their early years in a heterosexual household. More recently, however, studies were sporadically carried out among children who were raised from birth in a lesbian relationship. As early childhood experiences are believed to have an important impact on future development, the study of these newly created families provides a challenge for existing psychological theories. Although many important research questions have yet to be addressed, the results of all reviewed studies were unanimous; none of the investigations could identify an adverse effect of lesbian motherhood on child development.

Understanding human sexuality--specifically homosexuality and the paraphilias--in terms of chaos theory and fetal development

This paper considers human sexual orientation, specifically homosexuality and some paraphilias, to occur as a result of intrauterine development, itself a mathematically chaotic process. Parameter space, an example of state space in the phase diagram, has been used to illustrate different phenotypes. The crossing of a bifurcation boundary by the developing fetus is proposed as a mechanism by which it may be changed from one sexual orientation to another, e.g. from heterosexuality to homosexuality. The factors which push the fetus over a bifurcation boundary, which include a Y-chromosome, specific hormone administration, the lying contiguous to an opposite-sex fetus in multiple pregnancies, maternal stress and immune factors are described. The syndromes congenital renal hyperplasia and the androgen insensitivity syndrome and their relevance to this model are also discussed. Finally, chaos theory is used to encompass the complex interactions between fetal development and cultural factors in human sexuality.

Molecular Genetics of Mental Disorders with Particular Reference to Affective Disorders

The present article reviews the recent molecular genetic findings in affective disorders. Results of linkage and association studies are discussed in regard to the main limitations of these approaches in psychiatric disorders. On the whole, linkage and association studies contributed to the localisation of some potential vulnerability genes for Bipolar affective disorder on chromosomes 18, 5, 11, 4, 21 and X. The hypothesis of anticipation in affective disorders is also considered in light of interesting results with trinucleotide repeat mutations.

Why we cannot conclude that sexual orientation is primarily a biological phenomenon

While all mental phenomena must have an ultimate biological substrate, the precise contribution of biological factors to the development of sexual orientation remains to be elucidated. Does biology merely provide the slate of neural circuitry upon which sexual orientation is inscribed by experience? Do biological factors directly wire the brain so that it will support a particular orientation? Or do biological factors influence sexual orientation only indirectly, perhaps by influencing personality variables that in turn influence how one interacts with and shapes the environment as it contributes to the social relationships and experiences that shape sexual orientation as it emerges developmentally? Recent neurostructural and genetic linkage evidence pertaining to sexual orientation must be viewed tentatively until it has been adequately corroborated and integrated with psychological and cultural models. Moreover, even a reliable and robust correlation between a biological marker and sexual orientation would be equally compatible with the second and third possibilities delineated above. Yet if the third possibility more closely approximates reality, the search for predisposing biological factors will result in incomplete and misleading findings until their interactions with environmental factors are taken into account and controlled for in adequate longitudinal studies.

Biodemographic comparisons of homosexual and heterosexual men in the Kinsey Interview Data

Relations between sexual orientation and several biodemographic variables previously reported to differentiate between homosexual and heterosexual men were examined. Subjects were 4948 white, postpubertal males, who were never reared in foster homes, orphanages, or other institutions, and were never arrested or convicted on criminal charges. These were dichotomously classified as homosexual (n = 844) or heterosexual (n = 4104). Data came from survey interviews conducted by staff members of The Kinesey Institute for Research in Sex, Gender, and Reproduction from 1938 to 1963. Results extended previous findings that, compared with heterosexual controls, homosexual men have a later birth order, an earlier onset of puberty, and a lower body weight. Sexual orientation was weakly related or unrelated to height, paternal age, and sibling sex ratio. A more detailed analysis of the late birth order of the homosexual group showed that homosexual men have a greater number of older brothers than do heterosexual men, but they do not have a greater number of older sisters, once their number of older brothers has been taken into account.

Birth order and sibling sex ratio in two samples of Dutch gender-dysphoric homosexual males

Two studies were undertaken to confirm the previous findings that homosexual men in general tend to have a later than expected birth order and that extremely feminine homosexual men also tend to have a higher than expected proportion of brothers (i.e., a higher sibling sex ratio). Subjects in Study 1 were Dutch, adult and adolescent, biological male patients with gender dysphoria (persistent and recurrent desires to belong to the opposite sex), who were undergoing treatment with feminizing hormones. These comprised 83 patients who reported sexual attraction to other males (the homosexual group) and 58 who reported sexual attraction to females or equal attraction to males and females (the non-homosexual group). Subjects in Study 2 were Dutch adolescent male patients at another hospital. The homosexual group consisted of 21 gender-dysphoric homosexual teenagers referred to a gender identity clinic for children and adolescents. The control group were 21 adolescent males referred to the child psychiatry department of the same hospital for reasons other than gender identity disorder, homosexuality, or transvestism. These were individually matched to the homosexual subjects on age and sibship size. In both studies, the homosexual group had a significantly later average birth order than the comparison group. In Study 1, the homosexual group had a significantly elevated sibling sex ratio; this was not tested in Study 2 because of its small sample size. These studies add to the mounting evidence that late birth orders are common to all homosexual samples and that elevated sibling sex ratios are an additional characteristic of extremely feminine ones.

Genetic dissection of sexual orientation: behavioral, cellular, and molecular approaches in Drosophila melanogaster

Insertional mutagenesis using P-element vectors yielded several independent mutations that cause male homosexuality in Drosophila melanogaster. Subsequent analyses revealed that all of these insertions were located at the same chromosomal division, 91B, where one of the inversion breakpoints responsible for the bisexual phenotype of the fruitless (fru) mutant has been mapped. In addition to the altered sexual orientation, the fru mutants displayed a range of defects in the formation of a male-specific muscle, the muscle of Lawrence. Since the male-specific formation of this muscle was dependent solely on the sex of the innervating nerve and not on the sex of the muscle itself, the primary site of action of the fru gene should be in the neural cells. satori, one of the P-insertion alleles of fru which we isolated, carried the lacZ gene of E. coli as a reporter, and beta-galactosidase expression was found in a subset of brain cells including those in the antennal lobe in the satori mutant. Targeted expression of a sex determination gene, transformer (tra), was used to produce chromosomally male flies with certain feminized glomeruli in the antennal lobe. Such sexually mosaic flies courted not only females but also males when the DM2, DA3 and DA4 glomeruli were feminized, indicating that these substructures in the antennal lobe may be involved in the determination of the sexual orientation of flies. Molecular cloning and analyses of the genomic and complementary DNAs indicated that transcription of the fru locus yields several different transcripts, one of which encodes a putative transcription regulator with a BTB domain and two zinc finger motifs. In the 5' non-coding region, three putative Transformer binding sites were identified. It appears plausible therefore that the fru gene is one of the elements in the sex determination cascade that controls sexual fates of certain neuronal cells. Improper sex determination in these neural cells may lead to altered sexual orientation and malformation of the male-specific muscle. Some implications of the results of our study on sexual orientation in other organisms will be discussed based on the Drosophila research.

Errors by the American Psychiatric Association, the American Psychological Association, and the National Educational, Association in representing homosexuality in amicus briefs about Amendment 2 to the U.S. Supreme Court

In October 1995, consortiums of psychiatric and educational profes sional organizations, including the American Psychological Association and the American Psychiatric Association and the National Educational Association, submitted amicus briefs to the U.S. Supreme Court asserting that the scientific literature unequivocally supports the following propositions (a) that homosexuals, including homosexual teachers, do not disproportionately molest children, (b) that children of homosexual patients are not more likely to become homosexuals, (c) that professionals agree that homosexuality is not a pathology, and (d) that homosexual attractions are biologically or genetically predetermined and are therefore beyond the control of the individual. The first two contentions are inconsistent with the scientific literature, and the second two grossly oversimplify a contentious and uncertain literature.

Two types of fetishism

This study attempted to differentiate two clinical types of fetishism-fetishism proper and tranvestism-and to determine if tranvestites are truly fetishistic. The transvestites were further divided into gender-conforming and gender-noncomforming groups according to their score on a gender identity scale. These groups were compared using a self-report scale measuring fetishistic interests, and a set of questionnaire items regarding their childhood history, parental characteristics, and their emotional closeness with their parents. In addition, the penile responses of a subset of fetishists and tranvestites were recorded while they were presented with visual depictions of female and male public regions and potentially fetishistic objects (nylon stockings, female and male shoes, panties, male underwear, female and male feet). The fetishists proper and the transvestite subgroups did not differ from each other in terms of self-reported fetishistic interest or childhood and family histories. Moreover, there were no differences between these groups in their penile response to the potentially fetishistic stimulus they were most aroused by, relative to the depictions of the pubic region of their preferred gender. These results suggest that transvestites are in fact fetishistic, and that they are difficult to distinguish from fetishists proper.

A synaptobrevin-like gene in the Xq28 pseudoautosomal region undergoes X inactivation

The X and Y chromosomes that maintain human dimorphism are thought to have descended from a single progenitor, with the Y chromosome becoming largely depleted of genes. A number of genes, however, retain copies on both X and Y chromosomes and escape the inactivation that affects most X-linked genes in somatic cells. Many of those genes are present in two pseudoautosomal regions (PARs) at the termini of the short (p) and long (q) arms of the sex chromosomes. For both PARs, pairing facilitates the exchange of information, ensuring the homogenisation of X and Y chromosomal material in these regions. We report here a strikingly different regulation of expression of a gene in Xq PAR. Unlike all Xp PAR genes studied so far, a synaptobrevin-like gene, tentatively named SYBL1, undergoes X inactivation. In addition, it is also inactive on the Y chromosome, thereby maintaining dosage compensation in an unprecedented way.

Localization of the mouse gene releasing sex-limited expression of Slp

To probe genetic variation in the regulation of sexual dimorphism, we have characterized the mouse protein Slp, coded by the gene sex-limited protein (Slp). Slp expression in many strains is limited to males and is androgen-dependent. However, female expression is also observed in rare strains, due to nonlinked gene(s) termed regulator of sex-limitation (rsl). In this report we demonstrate that female expression of Slp results from homozygous recessive allele(s) at a single autosomal locus that maps to a 2.2-centimorgan interval on chromosome 13. This conclusion was supported by extensive genetic analyses including the use of polymorphic microsatellites to type numerous backcross progeny and a recombinant inbred series and to identify the congenic interval in three independently derived congenic strains. Four attractive candidate genes were identified by the localization of rsl. Interestingly, rsl was found not only to enable expression in females but to also increase expression in males. The findings suggest that the expression of Slp and perhaps other sexually dimorphic proteins is regulated by two pathways, one that is dependent upon rsl but not androgens and another that is rsl-independent but requires androgens.

Prenatal predisposition and the clinical management of some pediatric conditions

Theoretical understanding of psychosexual development, particularly in regard to sexual identity, has undergone several historical changes. Most notable has been the transition away from a learning paradigm, which held that individuals are psychosexually neutral at birth and that they develop their sexual identity due to rearing. This has shifted to contemporary acceptance that an interaction of both nature and nurture is responsible for psychosexual development. That there probably exists an inherent predisposition or bias toward a male or female identity, which is inferred by prenatal influences, is also current theory. However, while this shift has occurred in the theoretical understanding of the phenomenon, a comparable shift has not occurred in the clinical management of individuals where sex assignment or reassignment is a real issue. The theoretical change and real case management should be concordant.

Cerebral laterality in homosexual males: preliminary communication using magnetoencephalography

MEG-based auditory M100 source location in the left and right hemispheres of 8 strictly homosexual and 9 strictly heterosexual males were compared to determine if this measure of interhemispheric laterality varies as a function of sexual orientation. MEG fields evoked by auditory tone pips were recorded from left and right hemispheres in response to contralateral ear stimulation. The source of the 100-msec latency component, generated in the superior temporal gyrus, was estimated using a least squares inverse solution algorithm. Auditory sources in heterosexual men were significantly further anterior in the right hemisphere compared to the left hemisphere. Source locations in the homosexual men did not exhibit significant interhemispheric asymmetry, being similarly located in both hemispheres. Findings suggest an anatomic and/or functional difference in the superior temporal gyrus of at least some homosexual men.

How is the Human Genome Project doing, and what have we learned so far?

In this paper, we describe the accomplishments of the initial phase of the Human Genome Project, with particular attention to the progress made toward achieving the defined goals for constructing genetic and physical maps of the human genome and determining the sequence of human DNA, identifying the complete set of human genes, and analyzing the need for adequate policies for using the information about human genetics in ways that maximize the benefits for individuals and society.

Linkage between sexual orientation and chromosome Xq28 in males but not in females

We have extended our analysis of the role of the long arm of the X chromosome (Xq28) in sexual orientation by DNA linkage analyses of two newly ascertained series of families that contained either two gay brothers or two lesbian sisters as well as heterosexual siblings. Linkage between the Xq28 markers and sexual orientation was detected for the gay male families but not for the lesbian families or for families that failed to meet defined inclusion criteria for the study of sex-linked sexual orientation. Our results corroborate the previously reported linkage between Xq28 and male homosexuality in selected kinships and suggest that this region contains a locus that influences individual variations in sexual orientation in men but not in women.

An extension of the Maximum Lod Score method to X-linked loci

The Maximum Lod Score method for affected relative-pair analysis, introduced by Risch, is a powerful method for detecting linkage between an autosomal marker locus and disease. In order to use the method to detect linkage to markers on the X-chromosome, some modification is necessary. Here we extend the method to be applicable to X-chromosomal data, and derive genetic restrictions on the haplotype-sharing probabilities analogous to the 'possible triangle' restrictions described by Holmans for the autosomal case. Size criteria are derived using asymptotic theory and simulation, and the power is calculated for a number of possible underlying models. The method is applied to data from 284 type 1 diabetic families and evidence is found for the presence of one or more diabetogenic loci on the X-chromosome.

Genetic analysis of type 1 diabetes using whole genome approaches

Whole genome linkage analysis of type 1 diabetes using affected sib pair families and semi-automated genotyping and data capture procedures has shown how type 1 diabetes is inherited. A major proportion of clustering of the disease in families can be accounted for by sharing of alleles at susceptibility loci in the major histocompatibility complex on chromosome 6 (IDDM1) and at a minimum of 11 other loci on nine chromosomes. Primary etiological components of IDDM1, the HLA-DQB1 and -DRB1 class II immune response genes, and of IDDM2, the minisatellite repeat sequence in the 5' regulatory region of the insulin gene on chromosome 11p15, have been identified. Identification of the other loci will involve linkage disequilibrium mapping and sequencing of candidate genes in regions of linkage.

Development and familiality of sexual orientation in females

The development and familial clustering of sexual orientation were studied in 358 heterosexual, bisexual, and homosexual women. Sexual orientation, as measured by the Kinsey scales, was diverse yet showed statistical congruity and stability over a 1- to 1.5-year time span. Developmental patterns, as measured by retrospective reports on the ages of first sexual or romantic attraction and of self-acknowledgement of sexual orientation were very similar in the heterosexual and lesbian subjects except for the difference in object choice. The bisexual subjects displayed intermediate patterns that were more similar to the heterosexuals' on most facets yet closer to the lesbian subjects' on other dimensions. Familial clustering of nonheterosexual orientation was significant. Using two criteria, elevated rates of nonheterosexuality were found in four classes of relatives: sisters, daughters, nieces, and female cousins through a paternal uncle. The current data are not sufficient to distinguish between genetic and shared environmental sources of this familial aggregation. We discuss the possibility of using developmental criteria to differentiate between inherited and cultural sources of variation in female sexual orientation.

Sexual orientation and performance on sexually dimorphic motor tasks

Performance of homosexual and heterosexual men and women on two motor tasks which reliably demonstrate sex differences in opposite directions was examined. A Throw-to-Target Task and the Purdue Pegboard were administered to undergraduate students matched for age and program of study. A two-way ANOVA (Sex x Sexual Orientation) of the Throw data showed a significant interaction, F(1, 90) = 16.22, p < or = 0.001, and a trend for an effect of sex, F(1, 90) = 3.72, p < 0.06. Heterosexual men outperformed heterosexual women, whereas gay men threw less accurately and lesbians tended to throw more accurately than their heterosexual counterparts. Differences in sports history or hand strength did not account for these effects. Analysis of the Pegboard scores found no interaction or main effect of sexual orientation, but the effect of sex was significant, F(1,63) = 7.01, p < or = 0.02. Regardless of sexual orientation, women outperformed men and this difference remained significant even when a measure of finger size was partialed out. This study provides new evidence suggesting an association between sexual orientation and motor-performance profiles. As with cognitive tasks, the motor-performance profiles of homosexuals are composites of some male-typical and some female-typical abilities. To the extent that sociological factors have been controlled, the study suggests that both sexual orientation and motor/cognitive predispositions may have early biological contributions.

Evolutions of an orientation concerning the nature of the male homosexualities

None of the adults I have treated have had major disturbances in their sexual identity except for the selection of the sex of the person with whom they express their sexual feelings. Only one lives out a role that is ambisexual. All the men I have seen have been able to relate sexually to women with varying degrees of comfort. Six have had sexual intercourse with women and can function physiologically but without a sense of closeness or satisfaction, and five have been able to achieve climax. Some decided not to stay in their marriages, divorced, and adopted an overtly homosexual lifestyle. Some felt increasing ability to relate to women and decided to marry. Still others resolved current conflicts with their gay partners and felt no need for further therapy. All but one were actively employed and functioning well by external observation in demanding jobs requiring postgraduate college education. In terms of the detailed analytic work, there were no sets of insights that resulted in a major sexual partner reorientation. Those who decided to marry did so when they felt more able to resolve their narcissistic needs and make a relationship with a caring tolerant woman. They maintained their homosexual fantasies though the fantasies were more acceptable and less disruptive. It was not always the partner's penis that determined the sexual interest of these men. More often, it was the contour of the male body, the firmness of the musculature, the masculine bodily movements, the very identity and role of the father in the family. I did not see these foci of interest only as displacements from the genitals but rather as primary erotogenic stimuli. It is the seeking of a narcissistic object, the self in the other. This very orientation may be the innate variable. This position is spelled out in some detail by Leavy (1985). To varying degrees, the families of all these men were experienced as being composed of vigorous, active, articulate, determined, aspiring mothers and rather quiet, removed, passive fathers. The reported presence of this general pattern is impressive though the prominence of these characteristics differed from family to family. I have not postulated that these parental-child relations are causative in the boy's development of a homosexual life. However, they may be crucial if the genetic and/or constitutional factors discussed above are also present.(ABSTRACT TRUNCATED AT 400 WORDS)

To speak in chords about sexuality

Sexuality emerges from the interdependencies of biology, awareness, and the facts and artifacts of public life. A useful metaphor is that correct accountings of sexuality are not one-finger melodies--they are chords. Unfortunately, the physical vs. mental and nature vs. nurture controversies remain alive, well, and mischievous in regard to the correct understanding of human sexuality. Active political and legal disputes about homosexuality exemplify a continuing reliance on reductionistic models of the causes of conduct. Discourse relying on public misapprehension about biological causality can alter the course of subsequent science and public opinion and thus affect personal experience as well. Both dualistic and reductionistic models are traps and bar progress; the models should not be smuggled into accounts of sexuality.

Mapping genes for psychiatric disorders and behavioral traits

In the past year, some of the most exciting findings in the genetic investigation of mammalian behavior have been obtained through mapping and through gene manipulation studies in the mouse system. These include the localization of a gene for circadian periodicity in the mouse, gene knockouts of serotonin receptors, and the development of a transgenic model of Alzheimer's disease. The recent development of genetic maps covering the entire human genome and the implementation of new approaches to genetic analysis may now facilitate elucidation of complex behaviors in humans, particularly psychiatric disorders.

Does incest cause homosexuality?

A random sample of 5,182 adults from 6 U.S. metropolitan areas were questioned about incestuous sexual relationships during childhood. Incest was disproportionately reported by both male and female bisexuals and homosexuals. 148 gays (7.7% of the sample) reported 14 (50%) of same-sex, and 7 (22%) of opposite-sex incestuous experiences, and 20 (69%) of same-sex and 2 (3%) of opposite-sex sexual experiences with other relatives. 88 lesbians (3% of the sample) reported 2 (33%) of same-sex incest and 7 (9%) of opposite-sex incest and 1 (17%) of same-sex and 10 (13%) of opposite-sex sexual experiences with other relatives. 12% of 98 male homosexuals vs 0.8% of 1,224 male heterosexuals with a brother reported brother-brother incest. These findings are consonant with those of other studies in which disproportionately more incest by homosexuals was reported. As opposed to an evolutionary genetic hypothesis, these data support the alternative that homosexuality may be learned, since homosexuals do not produce children at sustainable levels and the incidence of homosexuality varies as a function of various social factors. Incest cannot be excluded as a significant basis for homosexuality.

Homosexuality, type 1: an Xq28 phenomenon

Despite the absence of phenotypic manifestations in alternating generations characteristic of X-linked disorders, a thesis is presented that a major type of Kinsey grades 5 and 6 male homosexuality is determined by a gene in the Xq28 region. A total of 133 families in 78 kinshps of male and female homosexual probands, in addition to 116 families (including those of 40 famous homosexuals) from the literature, revealed an unbalanced secondary sex ratio in the maternal generation of male, but not of female, homosexuals. On the maternal side, in this study, the ratio of all uncles to all aunts of 90 males homosexuals was 132/209, chi 2 = 8.52, p = 0.004. On the maternal side for the total of all sources, the ratio of uncles to aunts of male homosexuals was 241/367, chi 2 = 13.20; p < 0.0001. The male/female ratio of the total number of maternal sibships bearing homosexuals (310/628: 0.491) was a measure of fetal wastage of the mothers' male sibs; 49%. This ratio was very close to that of the total number of children born to fathers affected with any one of nine Xq28-linked male semilethal conditions (255/508: ratio 0.556); for the difference between the two populations chi 2 = 0.859, p = 0.354. The male/female ratio of the total number of children born to female carriers of any one of these same conditions (1,232/1,062: ratio 1.16), chi 2 = 13.8 p < or = 0.0001, is close to that of the total number of children in homosexual sibships: 511/413, chi 2 = 10.4, p = 0.005. Between the number of children born to Xq28 mothers and to those born of mothers of homosexuals chi 2 = 0.581, p = 0.446. One may readily surmise that the maternal influence so often related to homosexuality may lie in the mother being a genetic carrier, with traits thereto associated. In this study, 65% of the mothers of homosexuals had no or only one live-born brother. Additional support for a genetic hypothesis is found in the occurrence of multiple instances--almost exclusively among maternal relatives--of infertility, spontaneous abortions, miscarriages, stillbirths, remaining single past age 30, and suicide. Of 109 male and 43 female homosexual index cases in the present series there were 6 instances of brother/sister homosexual sibships.(ABSTRACT TRUNCATED AT 400 WORDS)

Genetic feminization of brain structures and changed sexual orientation in male Drosophila

The neural basis of sexual orientation in Drosophila was studied by the production of males with regionally feminized brains. Such flies express the female form of the sex determination gene transformer in a limited number of neurons under the control of GAL4 enhancer trap inserts. This method facilitated the creation of lines with a stable pattern of feminization. In tests of sexual preferences, flies that were feminized in a portion of the antennal lobes or in a subset of the corpora pedunculata (mushroom bodies) courted both males and females. These two brain structures, both of which are involved in olfactory processing, may function in the recognition of sex-specific pheromones, in the control of sex-specific behaviors, or both.

The rise of neurogenetic determinism

Dramatic advances in neuroscience are changing and enriching our understanding of brain and behaviour. But reductionist interpretations of these advances can cause great harm.

Abortion and the ethics of genetic sexual orientation research

Reports about possible genetic bases of homoerotic sexual orientation in adults have received a kind of schizophrenic social reception. On the one hand, these reports have been welcomed by some gay men and lesbians as biological confirmation of the commonly held view that sexual orientation is an involuntary trait, that sexual orientation is not in any meaningful sense chosen. Simon LeVay has received mail from thankful correspondents who welcomed his 1991 report about the possible neuroanatomical basis for male homoerotic sexual orientation, and some legal analysts see important implications of biological studies for the ways in which civil rights are recognized, especially those that depend on an immutable characteristic like race or gender.

The sexoanalytical treatment of ego-dystonic homosexuality

After clarifying some definitions, the author attempts to identify homosexuality through the sexual individuation process and to trace its various ontogenetic inconsistencies. Two clinical case studies are provided to further illustrate the sexoanalytic treatment of ego-dystonic homosexuality.

Measuring environmental/biological attribution: a fundamental dimension?

Explanations for behaviors that emphasize the importance of biological or environmental factors have been a major theme in psychological discourse, yet they have not been adequately explored as attributional styles with distinct correlates. The present two studies examined this dimension of attribution through the systematic development and validation of the Environmental/Biological Attribution Scale (EBAS). A total of 602 Canadian university students took part in the research project. The research confirmed four hypotheses: Biologically oriented attributional styles were significantly correlated with the same styles as measured by an alternate form (r = .76), with authoritarianism (r = .25), and with racism (r = .15). Environmentally oriented attributional styles were significantly correlated with attributions concerning the importance of strength of will (r = .39).