Yes, my mother used to (she now sculpts) teach French and Latin. And I, like Jérôme, and like one of my brothers, went to Polytechnique.
Do I consider us as having had upper class upbringing? Not really. My father is a doctor, OK, but because he wanted to be purely ethical his practice took a while to make any money. Around when I was 8 there was a time when he was not even making enough to cover the repayment of the equipment. So we were 4, living on less than the salary of my mother, who had the lowest rank of teacher that you can have.
I got first-hand clothes for the first time around the age of 13. And I'm a first child.
So, upper class no (OK, they are upper middle-class NOW, but I have long finished my studies). But child of parents who valued achievements at school certainly.
Teachers are not very well paid. If their profession helps them helping their children succeed (not so much my personal case -my mother wasn't teaching us anything at home, just encouraging us to read, not that I needed much encouragement), I won't begrudge them. And I wouldn't call it class reproduction in a hurry.
Now, it's true that the system used to be better at identifying potential wherever it came from. I will always do my best to contribute to that, because it is a very worthy cause. I don't think it's necessarily lost forever, and in any case even as it is now, France is far, far from English speaking countries in the equality of its school system. In France, you CAN study while poor without being burdened by huge debts. I think the main problem is that real estate has shot up, and it's very hard to live close to good schools at the moment if you are not well off. This will in fact be made only worse by the Sarkozy push to remove the 'carte scolaire'. "The womb that spawned that thing is fertile yet"
It is a subculture, it reproduces.
Of course, France's national ideology denies the existence of subcultures. A vivid image of what should exist acts as a surrogate for reality. Pursuit of the image then prevents pursuit of the reality -- John K. Galbraith
First, social position comes not only from economic capital, but also from cultural capital (mastering of language, culture, knowledge of social codes, social skills, diplomas...), and social capital (social links, networks...) as well as symbolic capital which is institutional recognition. Teachers' (and doctors') children, even when they are not economically rich, usually have a much higher cultural capital as well as a stronger social capital than workers and low-level employees. Also, teacher and doctor are symbolically more valued in the collective representations of the social system.
Second, for teachers, there is an insider's advantage: they know quite well the functioning of the national educational system. Combined with their specific social capital (networks), this makes them able to help their children to find the best ways within the educational system.
That doesn't mean we have to blame them for that: they do their best as parents to help their children. But it explains why teachers' children are overrepresented at the top of the French educational system.
"Ne te courbe que pour aimer..." René Char
If culture is a good indicator of success, I would say that is a desirable situation. Far more desirable than if it is parents' wealth. For example, you would be unlikely to see people with no culture, like Bush or Sarkozy, rising to the top (my inclusion of Sarkozy is also to show that I am afraid that culture is not the top factor in determining success even in France).
As for getting culture, well, the French system forces you to study many subjects for long (unlike A-level where you can take as few as 3 subjects). So if a child is a cultural sponge, he will be exposed to it and will have chance to absorb it. I sure have seen people from very humble backgrounds with a desire to learn. When they are children, they are the ones Jérôme was talking about when he said that the system used to identify bright kids everywhere.
I, personally, find it a very good thing when teacher's children are overrepresented at the top (except for the insider's argument. I don't know how much of an impact it has, my mother never ever used any network, but one case does not a statistic make). It means that positions may be earned rather than bought. It means that people chosing a career where they must care for others may sometimes benefit from it. It meast that opening the minds of your children may pay off.
One should not forget how you get in a Grande Ecole. It's a competitive exam, and anonymous. You can't convince teachers to make your child look good in return for contribution to the school. You can't get in because your parents got in, and so on. No system is perfect, but that one is fairer than most. "The womb that spawned that thing is fertile yet"
Statistically, at birth, their is an equivalent number of "cultural sponges" or children "with a desire to learn" in every socio-economic category (unless you think the social structure is genetically determined). But children coming from workers or low-level employees backgrounds have much stronger cultural and social liabilities. "Ne te courbe que pour aimer..." René Char