Suchergebnisse

In my comments on Townsend's detailed critique of Sulloway's (1996) book, I want to make two general points about birth order research. The first is that several authors—including Ernst and Angst (1983), who are extensively quoted by Townsend—have concluded that the effects of birth order on adult personality and behavior are either completely nonexistent or else so negligible as to be useless to science. I agree that the methodology of birth order studies is often flawed, and that many, if not most, of their findings are probably irreproducible. However, an assertion that birth order has no effect on adult behavior would be as extreme in its way as the assertion that birth order's effect on behavior is decisive. My own research demonstrates that a categorical dismissal of any and all birth order effects is not only premature but demonstrably erroneous.

This study's first objective was to compare the mean birth weights of homosexual and heterosexual men and women. Its second objective was to investigate whether prior male and female fetuses have different effects on the birth weight of subsequent fetuses. The subjects were 3229 adult men and women (the probands), who weighed at least 2500 g at birth, and whose mothers knew the sex of the child (or fetus) for each pregnancy prior to the proband. Information on birth weight, maternal gravidity and other demographic variables was reported on questionnaires completed by the probands' mothers. The results confirmed earlier reports that boys with older brothers weigh less at birth than boys with older sisters, but they did not confirm reports that girls with older brothers weigh less than girls with older sisters. The results did not show across-the-board differences in the mean birth weights of homosexual versus heterosexual women or homosexual versus heterosexual men. However, the homosexual males with older brothers weighed about 170 g less at birth than the heterosexual males with older brothers. It is suggested that this pattern of results may reflect a maternal immune response to Y-linked minor histocompatibility antigens (H–Y antigens). According to this hypothesis, when the maternal immune response is mild, it produces only a slightly reduced birth weight, but when it is stronger, it produces a markedly reduced birth weight as well as an increased probability of homosexuality.

Previous studies have shown that homosexual men erotically attracted to physically mature partners (androphiles) reach puberty earlier, on average, than comparable heterosexual men. This study investigated whether the same early onset of puberty is observed in homosexual men attracted to children (pedophiles) or to pubescents (hebephiles). Subjects were 721 white, male, convicted sexual offenders, originally part of a large-scale study of sexual offending. Homosexual offenders against adults reached puberty earlier than heterosexual offenders against adults, and homosexual offenders against pubescents reached puberty earlier than heterosexual offenders against pubescents. In contrast, there was no difference between the homosexual and the heterosexual offenders against children on this variable. These results suggest that homosexual hebephilia has more etiological factors in common with androphilia than does homosexual pedophilia.

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.

The purpose of this study was to investigate whether the well-established relationship between parity and birth weight is affected by the sex composition of siblings, especially for male newborns. Subjects were
856 male and 862 female newborns who weighed at least 2500 g at birth, who were born after 37 completed weeks of gestation, who obtained an Apgar score of 7 or higher, who had the same biological parents as all other children in the sibship, and who lived in the same household. Information on birth weight was collected from hospital records. Results showed that male newborns with older brothers weighed less than male newborns with older sisters. In contrast, the weight of female newborns with older brothers did not differ from the weight of female newborns with older sisters. One explanation of these results is that maternal immunoreactivity to some male-specific feature of the fetus affects prenatal development and consequently reduces birth weight in males. The relation between older brothers and birth weight may have theoretical significance for behavioural variables.

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.

There are at least two different criteria for assessing pedophilia in men: absolute ascertainment (their sexual interest in children is intense) and relative ascertainment (their sexual interest in children is greater than their interest in adults). The American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders, 3rd edition ( DSM-III) used relative ascertainment in its diagnostic criteria for pedophilia; this was abandoned and replaced by absolute ascertainment in the DSM-III-R and all subsequent editions. The present study was conducted to demonstrate the continuing need for relative ascertainment, particularly in the laboratory assessment of pedophilia. A total of 402 heterosexual men were selected from a database of patients referred to a specialty clinic. These had undergone phallometric testing, a psychophysiological procedure in which their penile blood volume was monitored while they were presented with a standardized set of laboratory stimuli depicting male and female children, pubescents, and adults.The 130 men selected for the Teleiophilic Profile group responded substantially to prepubescent girls but even more to adult women; the 272 men selected for the Pedophilic Profile group responded weakly to prepubescent girls but even less to adult women. In terms of absolute magnitude, every patient in the Pedophilic Profile group had a lesser penile response to prepubescent girls than every patient in the Teleiophilic Profile group. Nevertheless, the Pedophilic Profile group had a significantly greater number of known sexual offenses against prepubescent girls, indicating that they contained a higher proportion of true pedophiles. These results dramatically demonstrate the utility—or perhaps necessity—of relative ascertainment in the laboratory assessment of erotic age—preference.

Adult men's height reflects, not only their genetic endowment, but also the conditions that were present during their development in utero and in childhood. We compared the adult heights of men who committed one or more sexual offenses and who were erotically interested in prepubescent children (pedophilic sexual offenders; n=223), those who were erotically interested in pubescent children (hebephilic sexual offenders; n=615), and those who were erotically interested in adults (teleiophilic sexual offenders; n=187), as well as men who had no known sexual offenses and who were erotically interested in adults (teleiophilic nonoffender controls; n=156). The pedophilic and the hebephilic sexual offenders were significantly shorter than the teleiophilic nonoffender controls. The teleiophilic sexual offenders were intermediate in height between the nonoffenders and the pedophilic and hebephilic sexual offenders and not significantly different from any of the other groups. This suggests that—regardless of whatever psychological sequelae might also have followed from the conditions present during early development—pedophilic and hebephilic sexual offenders were subject to conditions capable of affecting their physiological development.