[quote]rainjack wrote:
A Meth addict has a different brain structure than a non addict. Does that mean Meth heads get special rights now as well? [/quote]
Keep reading. Did you get to the part about twin studies and direct genetic differences? I’ll be here when you get back (and your foot has been removed from said mouth):
Twin studies
In 1991, Bailey and Pillard studied three all male groups: identical twins, fraternal twins, and men with adoptive brothers.Of the 170 relatives examined, 52% of the identical twins were both gay, 22% of fraternal twins were both gay, and 11% of the adoptive brothers were both gay.
In 1992, Bailey and Pillard followed-up their experiment on homosexual men by studying identical twin, fraternal twin, and nongenetically related adopted sisters. As expected, their results mirrored those found in their gay brother study. Whereas only six percent of adopted sisters were both lesbian, sixteen percent of fraternal twin sisters and forty-eight percent of identical twin sisters were both lesbian . Clearly, the basis for a similar argument for predetermined homosexuality in women has been laid.
In 1993, Whitam, Diamond, & Martin found that 65% of identical twins were both gay, whereas only 29% of fraternal twins were gay.
Genetic differences
In 2004, Camperio-Ciani studied 98 homosexual and 100 heterosexual men and their relatives, which included more than 4,600 people overall. The female relatives on the mother’s side of the homosexual men tended to have more offspring than the female relatives on the father’s side. This suggests that women who pass on the gay trait to their male offspring are also more fertile. In comparison, the female relatives on both the mother’s and the father’s side of the heterosexual men did not appear to be as fertile, having fewer offspring.
In 2006, research published in the journal ?Human Genetics? found that the genetics of mothers of multiple gay sons act differently than those of other women. Scientists looked at 97 mothers of gay sons and 103 mothers without gay sons to see if there was any difference in how they handled their X chromosomes. They found that almost one fourth of the mothers who had more than one gay son processed X chromosomes in their bodies in the same way. Normally, women randomly process the chromosomes in one of two ways – half go one way, half go the other. The research “confirms that there is a strong genetic basis for sexual orientation, and that for some gay men, genes on the X chromosome are involved,” said study co-author Sven Bocklandt, a postdoctoral researcher at the University of California at Los Angeles. “When we looked at women who have gay kids, in those with more than one gay son, we saw a quarter of them inactivate the same X in virtually every cell we checked,” Bocklandt said. “That’s extremely unusual.”
