Anonymous wrote:OP here: yes, it's a real question. From what I've read from actual studies done on the subject, the majority of sibs test within 10 points of one another. Ours did not, and the child with the lower score performed lower than expected based on previous assessment information.
Your children are only 13 points apart. That is hardly a large discrepancy and within the normal variance. One is in the 99th percentile and one is in the 99.9th percentile. If you look at it that way, they are quite close.