Yaelle, I always find your POVs well-thought out and clearly expressed. The way I want to respond to this one is, "Well, yes and no." (At least I know what I think!)
I do know there's a lot of bad $#!+ in the environment that can affect our little younglings in their vulnerable early developmental stages. A quick google on keywords like "bisphenol-a," "endocrine disruptors," "xenoestrogen," and some combination of "oral contraceptives effluent groundwater watershed" will turn up a lot of disturbing stuff, including the fact that there are MALE fish and amphibians in river environments all over the USA which are now developing egg proteins in their testicles, and the sperm count is dropping precipitously for HUMAN MALES all over the globe.
This is not caused by bad parental values and People Magazine.
However.
In these cases of 10-year-old girls thinking they'd kinda maybe rather be boys, and vice-versa, it is rarely or never claimed that there is anything different about them physiologically --- and by this I mean brain physiology as well as sex organ physiology. These are not, by and large, kids who have genital anomalies or some kind of "hmm, that's funny" clinical marker of any kind.
As in this article, it's a kid who says, "I guess I feel like that other gender. Sometimes. Kinda."
Well. There is no way to "feel" a "gender." There is no way for a girl to know that she is or is not feeling the way a whole lot of other girls feel. Every person has a personal style and temperament, and feelings change, at some ages on a week-to-week basis. It's called "You're a kid. You're young yet."
A little boy who likes sequins on his clothes is not a little girl. He's a little boy who likes sequins. A little girl who likes hiking boots and dykey flannel plaids is not a boy (let alone a dyke!) She's just a little girl who likes boots and plaids.
"No, Tom, you're not a girl. You're a boy who feels inside the same way many boys feel. You're typical of boys of your temperament."
"No, Gwen, you're not a boy. You''re a girl who feels inside the same way millions of girls feel. You're just like so many other interesting girls of your personality type."
I rue the day the word "gender" escaped from the Grammar Corral and started galloping madly up and down Identity Avenue.
Kids should NOT be misled into thinking their varying sense of style has anything to do with intrinsic "boyness" or "girlness." Personal disclosure: I was a girl who didn't give a whit for clothes, hair and nails, romance novels or crushes upon selected Beatles. (This was the 60's) I grew up to be always and everywhere nothing other than a female. Oddities and all.
A note on gender. We all prob'ly klnow this, but...
Sex (and hence "boyness" and ""girlness") is neither "assigned" at birth nor "imposed" by society. It is "observed." And, in this age of routine sonograms, is usually observed before birth.
We saw --- observed --- detected --- recognized --- our firstborn son's sex as "male," hence his gender pronouns as "masculine," his destiny as "man," months before he was born.
Hint: it's the extra ornament.
(BTW this particular pic was not his, but his nephew's. For illustration, not documentation.)
Distinguishing simply between "male" and "female" is on its way to being a hate crime.