Depending on your age (and I wouldn't dare ask, of course), some of us may have also been affected by drugs frequently given pregnant women in the 50s era.
DES was commonly prescribed to prevent miscarriage. There is apparently evidence that this drug, which is a synthetic estrogen, may have bathed the developing child in estrogen during a couple of critical times that affect gender identity. High incidence of gender-ID disorder in those of us whose moms took DES.
Mine did and it would explain a few things...
Here's a clip from one publication which I found here:
http://www3.telus.net/des1/Observations.html
From - Simon Baron-Cohen's book "The Essential Difference, The Truth about the Male and Female Brain." Quotes from pages 99 and 98 respectively, Copyright 2003. Published by Basic Books (Amazon.com listing) 198).
"There was a time when women were prescribed a synthetic female hormone (diesthylstilbestrol) in an attempt to prevent repeated spontaneous miscarriages. Boys born to such women are likely to show more female typical behaviors enacting social themes in their play as toddlers, for example, or caring for dolls. This is a further indication that hormone levels can affect the ability to empathize."
"Most people who want to determine whether a person is male or female stop at this first level. But even if you are genetically female, and even if you are genitally female, you could be more male gonadally, and have a male brain and male sex-typical behavior. Conversely, even if you are genetically and genitally male, you could be more female gonadally, or you could have a female brain and female sex-typical behavior. And prenatal testosterone, an androgen, oozing from your testes if you are genetically and gonadally male, or dripping out of your adrenal glands if you are genetically and gonadally female, appears to be one important variable in determining your brain type or your sex-typical behavior.
There appear to be three points in development when testosterone secretion really surges. The first is the prenatal period, between eight and twenty four weeks into the pregnancy. The next one is around five months after birth. A final peak is at puberty. These periods are referred to as the "activational" periods, because it is at these times that the brain is thought to be most sensitive to such hormonal changes. The sex hormones are said to have a prenatal activating effect on the brain."
Dr. Baron-Cohen is a professor of psychology and psychiatry at Cambridge University.