Birth order & fetal androgen levels vs sexual orientation

Iggy Dalrymple · � #1 � 11-26-2007, 06:58 AM

Old news, but clear explanation.

Quote:

2D:4D ratio of homosexual men was not significantly different from that of heterosexual men for either hand (P > 0.09). However, segregating male subjects based on birth order provided support for the role of fetal androgens in male sexual orientation. The more older brothers a boy has, the more likely he is to develop a homosexual orientation2. Confirming these reports, we also found that only homosexual men had a greater than expected proportion of brothers (P< 0.01) among their older siblings (229 brothers:163 sisters) compared with the general population (106 males:100females6).

We found that the male 2D:4D ratio, which is unlikely to be influenced by social factors, also varies with the number of older brothers. The ratio was significantly more masculine in men with two or more older brothers than in men with no older brothers (Fig. 1b). There is also a significant correlation (r = -0.104; P < 0.05) between the number of older brothers and the right-hand 2D:4D ratio in men. If male subjects are divided by sexual orientation, the same pattern of later-born men displaying a more masculine 2D:4D is seen. Having older sisters has no apparent influence on male sexual orientation2, or on the 2D:4D ratio in men. No effect of older brothers or sisters on 2D:4D in women was observed, consonant with reports that older siblings exert no effect on female sexual orientation7.

Our results suggest that events before birth (or even before conception in the case of older brothers) influence human sexual orientation. The masculinized right-hand 2D:4D ratio in homosexual women may reflect fetal androgen levels that are slightly higher than in heterosexual women. Homosexual men without older brothers have 2D:4D ratios indistinguishable from heterosexual eldest sons, indicating that factors other than fetal androgen (such as genetic influences8, 9) also contribute to sexual orientation. Finger measures indicate that men with more elder brothers, including those men who develop a homosexual orientation, might be exposed to greater than normal levels of prenatal androgen.

Although hyper-androgenization of homosexual men might not fit some cultural expectations10, homosexual men display several hyper-masculine characteristics, including a greater mean number of sexual partners in a lifetime than heterosexual men, who in turn report more sexual partners than do women of either orientation. Furthermore, reports that adult homosexual men have more circulating androgens (ref. 11, but see ref. 12), larger genitalia13 and more 'masculine' auditory evoked potentials than heterosexual men14, are consistent with at least some homosexual men being hyper-androgenized.

Although it is possible that the maternal influence on finger growth of subsequent sons occurs after birth, a prenatal influence seems more likely because of the extensive physiological pairing of mother and fetus. The locus of the maternal 'memory' for previous sons, and the mechanisms by which fetal development of subsequent sons is altered, remain unknown. https://www.unl.edu/rhames/courses/re...mo_finger.html

I've known 1st born homosexual males. I also know two brothers who had a homosexual relationship and the older (1st born) was the more effeminate.

JonB · � #2 � 11-26-2007, 09:21 AM

I believe that stress in the first 7 weeks of pregnancy has a lot to do with sexual orientation of the fetus, but then again, I can't prove it.

bifrost99 · � #3 � 11-26-2007, 01:24 PM

In my college days in the '70s, a project we had in a speech class was group discussion, and the topic for our group was homosexuality. In the research we had available at that time, the big factor for development of homosexuality in males was a poor, or even bad, relationship with one's dad. Hormones, and even chromosomes, did not appear to be a significant factor.

I have had homosexual friends, classmates and students before and since that time, and I think the batting average for this cause (bad realtionship with father) is still 100%.

For sure, there are machos who have bad relations with their dads. But I still have to find one homosexual male who has or had a good relationship with his dad. Anyone know of someone?

Gerry

scorpiotiger · � #4 � 11-26-2007, 02:27 PM

and.. I know many guys that had a bad relationship with their dads that are not homosexual.

JonB · � #5 � 11-26-2007, 11:04 PM

Anyone know of someone?

Yes Jerry, I know 2 men who are gay, whose relationship with their Dad was great. Mind you, I don't know many gay men.

bifrost99 · � #6 � 11-28-2007, 01:34 PM

Quote:

Originally Posted by JonB

Anyone know of someone?

Yes Jerry, I know 2 men who are gay, whose relationship with their Dad was great. Mind you, I don't know many gay men.

Well, then that tends to disprove the theory.

But I still think that sexual orientation is a result of upbringing. I even wonder how the 2 men that you mention would become gay if their dad was doing his job well. (But then again, I recently saw a supposedly "responsible mom" claiming in a TV interview that she would not interfere with the sexual development of her kids. Duh?)

Now we have TV shows giving the impression to our children that homosexual behavior is something normal. US schools are even being made to discuss such "lifestyles" to the kids. (Yeah, all this again the result of the PC -- politically correct -- crowd.) So it shouldn't be any wonder if we have more and more homosexuals.

If children are raised knowing their roles based on their sex, then they would grow up knowing and behaving so. But if they are raised never knowing, or even being made to accept "alternative" lifestyles, then they would think their sex does not matter and they are free to behave as the opposite sex.

Just my ideas.

Gerry

bifrost99 · � #7 � 11-29-2007, 04:18 PM

Could homosexuality be just a fad? I think sexual preference can be simply a result of one's own decision.

Here's a news item. And to think this is going on in a Muslim populace.

Afghan boy dancers sexually abused by former warlords

In spite of the title, it deals with simple male homosexuality as an acceptable practice among the powerful warlords.

Gerry

Iggy Dalrymple · � #8 � 11-29-2007, 07:11 PM

Robert Joffrey, co-founder of the famous Joffrey Ballet, was of Afghan heritage.
His birth name was Abdulla Jaffa Anver Bey Khan.

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