Here is an interesting read from Men's Health on it. I'm replying to you because its clear LK has reading issues and I figured you'd find it interesting like I did.
http://www.menshealth.com/health/3-signs-you-started-as-girl
Yep, that is interesting. I was thinking about the Mexican (IIRC) kids who are raised as girls (and the ones I've seen are damned fine looking girls too) and then after marriage, find out they are genetically male, just got a double copy of a recessive gene. Can't have babies because they never expressed the proper female hormones either, but externally to the most detailed medical inspection they are female, and absent genetic testing the medical diagnosis is female with a relatively slight birth or developmental defect.
lol
Geebus wept.
Nobody starts out as a "girl". We start out as a blank slate that evolves into a girl or a boy at specific points dependent on testosterone. The release of testosterone is dependent on the male chromosome being present, ergo, without the male chromosome there would be no testosterone and the blank slate would develop into a female at the appropriate times.
Saying that embryos start out as a girl is like saying they start out as a fish since the same basic structure that can form gills develops glands, ears. But then again, I guess we can all just claim to be Fish now, if we want. Eh?
Saying there is ambiguity because we all originate from females is sheer idiocy. There is ambiguity because people want there to be and people can have mental issues. That's why there is ambiguity from a moral code perspective making some people serial murderers.
You can go ahead and take your BS article from Men's Health, the bastion of genetics, scientific, and developmental medical knowledge. I'll depend on basic biology that isn't dumbed down to the lowest common denominator.
He's not really saying that everyone is a girl embryo, but that everyone starts out as an embryo that except for genetic coding is identical to a female embryo. Only by defining sex as a Y chromosome is everyone not a female embryo. That's a LOT different from saying everyone starts out as a fish. It's certainly possible to be fishlike (many thalidomide babies were essentially just that) but not an actual, mostly functional fish. However, if one has certain genetic faults or developmental issues, a genetic male can easily become a perfectly or nearly perfectly functional female. We simply aren't THAT different.
It can even happen at puberty, for males born with 5-Alpha-Reductase Deficiency. These genetic males (it's mostly known from the Dominican Republic and Papua New Guinea) were perfect girls until puberty, complete with vaginas and undetectable as male even by doctors. Yet even though those males lacked the ability to produce functional 5-Alpha-Reductase enzyme which metabolizes testosterone into dihydrotestosterone which causes us to develop male sexual characteristics, at puberty another powerful enzyme comes online to kick start the process. These children had functional coding for 5-Alpha-Reductase type 1 (actually a different but similar enzyme) which began converting testosterone into dihydrotestosterone. As a result, these functional pubescent girls grew penises and testicles, vaginas closing up, and developed normal interest in "other" girls. They were now male, and many are male without any defects (i.e. they can breed and reproduce.) Others with additional genetic defects (specifically defective genes for 5-Alpha-Reductase type 1 or very low testosterone production for other reasons) never manifest male characteristics and are only discovered to be genetically male by accident or during fertility treatment trying to conceive.
http://ghr.nlm.nih.gov/condition/5-alpha-reductase-deficiency
Although we perceive people like Bruce Jenner as weird and bizarre because the vast majority of us are (and identify with) our outward appearance, in reality we aren't all that different, and in early development we're pretty much identical except at a genetic level. Sex, like sexual preference, is a much more complicated thing than a boy/girl binary switch, but our default, no expressed hormones form is female.