Birth Order and Sibling Sex Ratio of Children and Adolescents Referred to a Gender Identity Service

被引:28
作者
VanderLaan, Doug P. [1 ]
Blanchard, Ray [2 ]
Wood, Hayley [1 ]
Zucker, Kenneth J. [1 ,2 ]
机构
[1] Ctr Addict & Mental Hlth, Gender Ident Serv, Toronto, ON, Canada
[2] Univ Toronto, Dept Psychiat, Toronto, ON, Canada
基金
加拿大健康研究院;
关键词
OLDER BROTHERS; ORIENTATION; HOMOSEXUALITY; MEN; PREGNANCY; DNA; MICROCHIMERISM; PROPORTION; WEIGHT; PLASMA;
D O I
10.1371/journal.pone.0090257
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
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.
引用
收藏
页数:9
相关论文
共 52 条
[1]  
[Anonymous], THESIS U TORONTO
[2]  
[Anonymous], THESIS VRIJE U AMSTE
[3]   Kinetics of fetal cellular and cell-free DNA in the maternal circulation during and after pregnancy: implications for noninvasive prenatal diagnosis [J].
Ariga, H ;
Ohto, H ;
Busch, MP ;
Imamura, S ;
Watson, R ;
Reed, W ;
Lee, TH .
TRANSFUSION, 2001, 41 (12) :1524-1530
[4]   Opposite-sex twins and adolescent same-sex attraction [J].
Bearman, PS .
AMERICAN JOURNAL OF SOCIOLOGY, 2002, 107 (05) :1179-1205
[5]  
Bianchi DW, 2001, ANN NY ACAD SCI, V945, P119
[6]   Birth order and sibling sex ratio in two samples of Dutch gender-dysphoric homosexual males [J].
Blanchard, R ;
Zucker, KJ ;
CohenKettenis, PT ;
Gooren, LJG ;
Bailey, JM .
ARCHIVES OF SEXUAL BEHAVIOR, 1996, 25 (05) :495-514
[7]   BIRTH-ORDER AND SIBLING SEX-RATIO IN HOMOSEXUAL MALE-ADOLESCENTS AND PROBABLY PREHOMOSEXUAL FEMININE BOYS [J].
BLANCHARD, R ;
ZUCKER, KJ ;
BRADLEY, SJ ;
HUME, CS .
DEVELOPMENTAL PSYCHOLOGY, 1995, 31 (01) :22-30
[8]   SIBSHIP SIZE, SIBLING SEX-RATIO, BIRTH-ORDER, AND PARENTAL AGE IN HOMOSEXUAL AND NONHOMOSEXUAL GENDER DYSPHORICS [J].
BLANCHARD, R ;
SHERIDAN, PM .
JOURNAL OF NERVOUS AND MENTAL DISEASE, 1992, 180 (01) :40-47
[9]   Proportion of homosexual men who owe their sexual orientation to fraternal birth order: An estimate based on two national probability samples [J].
Blanchard, R ;
Bogaert, AF .
AMERICAN JOURNAL OF HUMAN BIOLOGY, 2004, 16 (02) :151-157
[10]  
Blanchard R, 1997, Annu Rev Sex Res, V8, P27