I mentioned in another post that nearly 25% of DD's new school is in Gifted Programs, but that they actually are smart, and probably all of them would be considered gifted. It just seems too weird, though, that 25% of the people at our school would be at where apparently only 2% of the general population are. The school has fairly strict criteria for entrance, which means getting at least at the 98th percentile on above grade level tests (ITBS, I believe, one year ahead), PLUS at least 130 on 2 sections of the CoGAT test and/or NNAT. I can believe that a "bright" person could get a good score on Achievement, or maybe the CoGATs, but both? It seems improbable that anyone at the 75th Percentile, or even the 90% would have solid 98% or 99% scores.
The 11-12 school she will go to when she gets to that age (in 9th grade now) is on the top 20 list of national merit scholar schools. It gets high scores on various state and national competitions. We live next to a few Engineering places, so one could assume that most engineers are either very bright or gifted, and they could have passed the genes on to children. About 75% (or more, she can't really estimate) of the kids in the gifted programs are Asian, but I can't really believe that any amount of "pressure" from parents would make them score in the gifted range, so I'm sure most of them are truly gifted. Does anyone have any input on if all of these students being gifted is feasible, statistically?

I think it's possible, assuming your school draws on a non-representative population in terms of socio-economic status. Your school probably has few or no kids who were exposed to drugs or (much) alcohol in the womb; most of them probably experienced enriched environments as toddlers; most of them probably have educated parents with relatively large vocabularies; and many of them probably come from families that value education. That's before we even get to the possibility of skewed genetics due to all those engineers!

This happens all the time in the US. I would guess that the only kind of neighborhood that IS unusual in the US is one that perfectly mimics the national average. We tend to live more 'mosaic' style.

Our area is very similar: large gifted program in the schools. The area I live in is upper class with lots of professionals and a large technical industry, but also professors from the large university. This said, I also see a lot of tutor sessions for the high school students in the local book stores. It is considered normal around here to have your child in tutoring sessions for their gifted classes. This makes me ponder are the students really all that gifted? The stakes are high in the district and the students have a lot of pressure on their shoulders to preform. Since the majority of the students are in gifted classes there is harassment directed towards the students who don't make the cut for the program. They treat them as if they are stupid instead of average intelligence. Really is sad to watch.

Same thing at our old school. Except all you had to do to be tagged GT in our district was achieve 92nd percentile on the NNAT. Something like 40%+ of kids in some grades were tagged. Which of course meant that tag meant nothing! The vast majority of those kids were bright, but certainly at grade level or close from what I could see. But it is a highly educated, high parental involvement area.

I've seen something similar at our school. Even though my kids go to a public school, there is a lot of self-selection. Many people buy houses in the boundary area because the test scores say it is an "excellent" school and because it has a gifted program. We also have a large population of people who have choice enrolled their kids form outside the neighborhood for the same reasons. In short, people who want their kids to go to an "excellent" school based on test scores and/or who believe that their kids are gifted seek out our neighborhood and our school. Consequently, we have a population that is skewed differently from many of the surrounding schools.