Ray Blanchard | University of Toronto (original) (raw)

Papers by Ray Blanchard

Journal of Gay & Lesbian Mental Health, Dec 29, 2010

The use of puberty-delaying or blocking hormonal treatment of adolescents with gender identity di... more The use of puberty-delaying or blocking hormonal treatment of adolescents with gender identity disorder (GID) has become increasingly common. In the present study, we examined demographic, behavior problem, and psychosexual measures to see if any of them correlated with the clinical decision to recommend, or not recommend, puberty-blocking hormonal therapy in a consecutive series of 109 adolescents (55 females, 54 males) with GID evaluated between 2000 and 2009. Of the 109 adolescents, 66 (60.6%) were recommended for puberty-blocking hormonal therapy and 43 (39.4%) were not. A combination of five (of 15) demographic, behavior problem, and psychosexual measures were identified in a logistic regression analysis to significantly predict this clinical recommendation. The quantitative data were complemented by clinical case descriptions and some follow-up information. We discuss our data in relation to the Dutch model of early biomedical treatment for youth with GID and consider areas that require further clinical and empirical examination.

Proceedings of The Royal Society B: Biological Sciences, Mar 18, 2020

The fraternal birth order effect (FBOE) is the finding that older brothers increase the probabili... more 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.

Journal of Biosocial Science, Oct 1, 1998

Homosexual men have a higher mean birth order than do heterosexual men, primarily because they ha... more 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.

Developmental Psychobiology, Oct 25, 2014

This study tested predictions regarding two hypothesized maternal immune responses influencing se... more This study tested predictions regarding two hypothesized maternal immune responses influencing sexual orientation: one affecting homosexual males with high fraternal birth order and another affecting firstborn homosexual individuals whose mothers experience repeated miscarriage after the birth of the first child. Low birth weight was treated as a marker of possible exposure to a maternal immune response during gestation. Birth weight was examined relative to sibship characteristics in a clinical sample of youth (N ¼ 1,722) classified as heterosexual or homosexual based on self-reported or probable sexual orientation. No female sexual orientation differences in birth weight were found. Homosexual, compared to heterosexual, males showed lower birth weight if they had one or more older brothersand especially two or more older brothers-or if they were an only-child. These findings support the existence of two maternal immune responses influencing male sexual orientation and possibly also cross-gender behavior and identity.

Proceedings of the National Academy of Sciences of the United States of America, Dec 11, 2017

Journal of Sex & Marital Therapy, Jul 11, 2016

Several studies indicate that homosexual males have a high proportion of older brothers compared ... more Several studies indicate that homosexual males have a high proportion of older brothers compared to heterosexual males. Natal males with gender dysphoria who are likely to be homosexual also display this sibship pattern. Until recently, there was little evidence linking homosexuality and/or gender dysphoria in females to unique sibship characteristics. Two studies have indicated that natal female youth clinically referred for gender dysphoria are more likely to be only children (Schagen et al., 2012 ; VanderLaan et al., 2014 ). However, these studies did not include control groups of youth clinically referred for other reasons. Thus, it is unclear whether the increased likelihood of only-child status is specific to gender-referred natal females. This study compared only-child status among youth referred to a mental health service for gender dysphoria (778 males, 245 females) vs. other reasons (783 males, 281 females). Prehomosexual gender-referred males were less likely to be only children than clinical controls. Contrary to previous findings, gender-referred females were not more likely to be only children, indicating that increased likelihood of only child status is not specific to gender-referred females, but is characteristic of clinic-referred females more generally.

Journal of Child Psychology and Psychiatry, May 1, 1998

PLOS ONE, Mar 20, 2014

In adult male samples, homosexuality is associated with a preponderance of older brothers (i.e., ... more In adult male samples, homosexuality is associated with a preponderance of older brothers (i.e., the fraternal birth order effect). In several studies comparing gender dysphoric youth, who are likely to be homosexual in adulthood, to clinical or non-clinical control groups, the findings have been consistent with the fraternal birth order effect in males; however, less is known about unique sibship characteristics of gender dysphoric females. The current study investigated birth order and sibling sex ratio in a large sample of children and adolescents referred to the same Gender Identity Service (N = 768). Probands were classified as heterosexual males, homosexual males, or homosexual females based on clinical diagnostic information. Groups differed significantly in age and sibship size, and homosexual females were significantly more likely to be only children. Subsequent analyses controlled for age and for sibship size. Compared to heterosexual males, homosexual males had a significant preponderance of older brothers and homosexual females had a significant preponderance of older sisters. Similarly, the older sibling sex ratio of homosexual males showed a significant excess of brothers whereas that of homosexual females showed a significant excess of sisters. Like previous studies of gender dysphoric youth and adults, these findings were consistent with the fraternal birth order effect. In addition, the greater frequency of only children and elevated numbers of older sisters among the homosexual female group adds to a small literature on sibship characteristics of potential relevance to the development of gender identity and sexual orientation in females.

Psychological Reports, Feb 1, 2003

Nicolosi and Byrd in 2002 summarized empirical research on birth order and sexual orientation in ... more Nicolosi and Byrd in 2002 summarized empirical research on birth order and sexual orientation in men, which research has documented that homosexual men have a later birth order than heterosexual men. They did not, however, note a more refined analysis of an earlier null finding by Siegelman. This 1998 reanalysis by Blanchard, Zucker, Siegelman, Dickey, and Klassen also confirmed the later birth order of homosexual men.

European Child & Adolescent Psychiatry, Mar 23, 1998

This study examined the birth order of girls with gender identity disorder (N = 22). Each proband... more This study examined the birth order of girls with gender identity disorder (N = 22). Each proband was matched to 3-7 clinical control girls for age at assessment and number of siblings (the mode number of controls per proband was 7) (total N = 147). The number of older brothers, older sisters, younger brothers, and younger sisters was recorded. Slater's birth order index showed that the probands were significantly more likely to be early born than were the controls. A modified Slater's index also compared the birth order of the probands and the controls only to their brothers (when they had one or more) and only to their sisters (when they had one or more). Compared to the controls, the probands were born early compared to their sisters, but not to their brothers. These findings are the inverse of two previous studies of boys with gender identity disorder, who were later born relative to clinical control boys (11), an effect that appeared to be accounted for primarily by being born later relative to older brothers, but not to older sisters (46).

Developmental Psychology, 1995

The purpose of this study was to extend the findings, previously limited to adults, that male hom... more The purpose of this study was to extend the findings, previously limited to adults, that male homosexuals have a greater than average proportion of male siblings and a later than average birth order. There were 2 matched groups of 156 probands. The homosexual–prehomosexual (HP) group included boys referred to a specialty clinic because of persistent cross-gender behavior plus homosexual adolescents

The Journal of Sexual Medicine, Mar 1, 2015

Introduction. The number of adolescents referred to specialized gender identity clinics for gende... more Introduction. The number of adolescents referred to specialized gender identity clinics for gender dysphoria appears to be increasing and there also appears to be a corresponding shift in the sex ratio, from one favoring natal males to one favoring natal females. Aim. We conducted two quantitative studies to ascertain whether there has been a recent inversion of the sex ratio of adolescents referred for gender dysphoria. Methods. The sex ratio of adolescents from two specialized gender identity clinics was examined as a function of two cohort periods (2006-2013 vs. prior years). Study 1 was conducted on patients from a clinic in Toronto, and Study 2 was conducted on patients from a clinic in Amsterdam. Results. Across both clinics, the total sample size was 748. In both clinics, there was a significant change in the sex ratio of referred adolescents between the two cohort periods: between 2006 and 2013, the sex ratio favored natal females, but in the prior years, the sex ratio favored natal males. In Study 1 from Toronto, there was no corresponding change in the sex ratio of 6,592 adolescents referred for other clinical problems. Conclusions. Sociological and sociocultural explanations are offered to account for this recent inversion in the sex ratio of adolescents with gender dysphoria. Aitken M,

Journal of Psychosexual Health, 2019

Journal of psychosexual health, Jul 1, 2019

increasing the odds of homosexuality by approximately 33%. It has been hypothesized that this fra... more increasing the odds of homosexuality by approximately 33%. It has been hypothesized that this fraternal birth order effect reflects the progressive immunization of some mothers to Y-linked minor histocompatibility antigens (H-Y antigens) by each succeeding male fetus and the concomitantly increasing effects of such maternal immunization on the future sexual orientation of each succeeding male fetus. According to this hypothesis, anti-H-Y antibodies produced by the mother pass through the placental barrier to the fetus and affect aspects of sexual differentiation in the fetal brain. This explanation is consistent with a variety of evidence, including the apparent irrelevance of older sisters to the sexual orientation of later born males, the probable involvement of H-Y antigen in the development of sextypical traits, and the detrimental effects of immunization of female mice to H-Y antigen on the reproductive performance of subsequent male offspring. The maternal immune hypothesis mi...

Archives of Sexual Behavior, 2013

Archives of Sexual Behavior, 2009

This paper contains the author's report on pedophilia, submitted on June 2, 2008, to the work gro... more This paper contains the author's report on pedophilia, submitted on June 2, 2008, to the work group charged with revising the diagnoses concerning sexual and gender identity disorders for the fifth edition of the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM). The author reviews the previously published criticisms and empirical research concerning the diagnostic criteria for pedophilia and presents criticism and relevant research of his own. The review shows that the DSM diagnostic criteria for pedophilia have repeatedly been criticized as unsatisfactory on logical or conceptual grounds, and that published empirical studies on the reliability and validity of these criteria have produced ambiguous results. It therefore seems that the current (i.e., DSM-IV-TR) diagnostic criteria need to be examined with an openness to major changes in the DSM-V.

The Journal of Nervous and Mental Disease, 1995

We show that numerical approximations of Kolmogorov complexity (K) of graphs and networks capture... more We show that numerical approximations of Kolmogorov complexity (K) of graphs and networks capture some group-theoretic and topological properties of empirical networks, ranging from metabolic to social networks, and of small synthetic networks that we have produced. That K and the size of the group of automorphisms of a graph are correlated opens up interesting connections to problems in computational geometry, and thus connects several measures and concepts from complexity science. We derive these results via two different Kolmogorov complexity approximation methods applied to the adjacency matrices of the graphs and networks. The methods used are the traditional lossless compression approach to Kolmogorov complexity, and a normalised version of a Block Decomposition Method (BDM) based on algorithmic probability theory.

The Fertility of Hebephiles and the Adaptationist Argument against Including Hebephilia in

Proceedings of the National Academy of Sciences of the United States of America, Jan 11, 2017

We conducted a direct test of an immunological explanation of the finding that gay men have a gre... more We conducted a direct test of an immunological explanation of the finding that gay men have a greater number of older brothers than do heterosexual men. This explanation posits that some mothers develop antibodies against a Y-linked protein important in male brain development, and that this effect becomes increasingly likely with each male gestation, altering brain structures underlying sexual orientation in their later-born sons. Immune assays targeting two Y-linked proteins important in brain development-protocadherin 11 Y-linked (PCDH11Y) and neuroligin 4 Y-linked (NLGN4Y; isoforms 1 and 2)-were developed. Plasma from mothers of sons, about half of whom had a gay son, along with additional controls (women with no sons, men) was analyzed for male protein-specific antibodies. Results indicated women had significantly higher anti-NLGN4Y levels than men. In addition, after statistically controlling for number of pregnancies, mothers of gay sons, particularly those with older brothers...