It's interesting how this happens, because there's definitely neighborhoods with a lot of kids about the same age. I can only assume it's the ways the markets function.

My neighborhood was full of kids growing up-- it was a brand-new housing development built to be compact and affordable that seemed to attract a lot of relatively young professionals who had recently started families and were in need of a cheap housing alternative.

In my town a lot of the more expensive housing might be snatched by kid-less couples, retired immigrants (I'm from Mexico, a lot of American immigrants move there to retire), etc.

Established neighborhoods will eventually see the older tenants move out (or, grimly enough, die off) but it happens in such a random fashion you never really see just a single influx of young families into the neighborhood, like you do with a brand-new development.