My DS and DD follow the sibling "rule" about IQ but their cognitive abilities are apples and oranges. They are within 10 points of each other's GAI but they are almost mirror images of each other in IQ. DD8 is DYS based on her VCI and DS11is HG in PRI and ADHD/dysgraphic. They each scored exactly the same on the other cognitive ability index, PRI/VCI respectively.
You would think they would be more "alike" based on their numerically similar IQs and genetics but they are almost different species in the way their minds work. Even when the numbers are "close" they can be as different as night and day!
