Family and Sexual Orientation: The Family-Demographic Correlates of Homosexuality in Men and Women (Report‪)‬

Introduction Recent research on family and sexuality concludes that the only biodemographic correlate of male sexual orientation is the number of older brothers (Blanchard & Bogaert, 1996; Bogaert, 2006). Nearly all studies find that older sisters have no effect on male homosexuality (Blanchard, 2001; Blanchard & Bogaert, 1996; Blanchard, Zucker, Siegelman, Dickey, & Klassen, 1998; Ellis & Blanchard, 2001). There is little to no evidence that any biodemographic variables correlate with female sexual orientation (Blanchard, 1997; Bogaert, 1997). These studies complement earlier studies that relate male homosexuality to birth order and intrafamily sex ratios (Blanchard & Sheridan, 1992; Blanchard & Zucker, 1994; Hare & Moran, 1979; Slater, 1962; Zucker & Blanchard, 1994).