The thing is typically if you are brought up playing chess you are surrounded by a family that does things that families (or a parent) that plays chess do. Like eat well, read to/with their kids, converse on various current topics, discuss history, etc. So the chess happens to be one of many things but as we like to say around here "correlation does not imply causation". In this case, playing chess isn't the reason people are more able at intellectual pursuits, it just happens to be one of many things they have been breast fed since young. In cases where youth chess clubs are established in "the hood", the kids can and do excel at chess but that doesn't translate necessarily into broad academic achievement, other than the effect that it can have in their belief in their own ability to achieve.