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Interesting piece on origins of sexual orientation

Lesley Stahl of 60 Minutes has a piece up from a segment called The Science Of Sexual Orientation.

There is a lot of discussion of genes vs. environment, but in the end, there is no question that the role of hormones within the womb have a profound effect, based on studies of twins. But then here’s a real weird bit of data:

While biologists look at hormones for answers about human sexuality, other scientists are looking for patterns in statistics. And hard as this is to believe, they have found something they call “the older brother effect.”

“The more older brothers a man has, the greater that man’s chance of being gay,” says Bailey.

Asked if that’s true, Bailey says, “That is absolutely true.”

If this comes as a shock to you, you’re not alone. But it turns out, it’s one of the most solid findings in this field, demonstrated in study after study.

And the numbers are significant: for every older brother a man has, his chances of being gay increase by one third. Older sisters make no difference, and there’s no corresponding effect for lesbians. A first-born son has about a 2 percent chance of being gay, and the numbers rise from there. The theory is it happens in the womb.

“Somehow, the mother’s body is remembering how many boys she’s carried before,” says Breedlove. “The favorite hypothesis is that the mother may be making antibodies when she sees a boy the first time, and then affect subsequent boys when she carries them in utero.”

It’s an an interesting read — and of course, nothing is definitive. You’ll also note, as always, lesbians aren’t discussed in much detail.

The more the Right bleats that somehow kids just “turn gay” because of a gay teacher, for instance, the more ludicrous they look.

Hat tip Holly.

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Pam Spaulding

Pam Spaulding