I wrote that given Blanchard's figure of a 33% increase in the odds of homosexuality with each additional older brother, Michael Sylvester's statement about the fraternal birth order effect wasn't too far off.
On 16 Mar 2006 at 4:39, Allen Esterson promptly replied: > I don't see Michael as writing that there is a 20% *increase* in the > chances of a male being gay if he has one older brother, etc. He > writes: "So a guy with one older brother has a 20% chance [of being > gay], two older brothers 40, and three older brothers 60% chance." > That's not at all close to what Blanchard and Bogaert say. Allen's right (Gad, that's hard to say). I misread something, hopefully Sylvester rather than Blanchard. Bogaert (2004) provides one of the figures we're looking for. He argues that the familiar figure of 10% homosexuality in the general population is too high, and a better estimate is around 2%. Here's what he then says: "We have quantified the strength of the fraternal birth order effect. Blanchard and Bogaert (1996b) found that each additional older brother increases the odds of homosexuality by 33% (c.f., Bogaert, 2003). Using this figure, Blanchard (2001) has shown that, based on a 2% prevalence of male homosexuality with no older brothers, the probability that a man will be gay rises to 6% for a man with 4 older brothers (vs. 0 older brothers), a three-fold increase." Stephen Bogaert AF. (2004). The prevalence of male homosexuality: the effect of fraternal birth order and variations in family size.J Theor Biol. 2004 Sep 7;230(1):33-7. ----------------------------------------------------------------- Stephen L. Black, Ph.D. Department of Psychology Bishop's University e-mail: [EMAIL PROTECTED] Lennoxville, QC J1M 1Z7 Canada Dept web page at http://www.ubishops.ca/ccc/div/soc/psy TIPS discussion list for psychology teachers at http://faculty.frostburg.edu/psyc/southerly/tips/index.htm ----------------------------------------------------------------------- --- You are currently subscribed to tips as: [email protected] To unsubscribe send a blank email to [EMAIL PROTECTED]
