I couldn't open the link above but this is info from Linda Silverman's website
http://www.gifteddevelopment.com/What_is_Gifted/learned.htmBrothers and sisters are usually within five or ten points in measured ability. Parents' IQ scores are often within 10 points of their children's; even grandparents' IQ scores may be within 10 points of their grandchildren's. We studied 148 sets of siblings and found that over 1/3 were within five points of each other, over 3/5 were within 10 points, and nearly 3/4 were within 13 points. When one child in the family is identified as gifted, the chances are great that all members of the family are gifted.
6. Second children are recognized as gifted much less frequently than firstborns or only children. They often go in the opposite direction of their older siblings and are less likely to be achievement oriented. Even the first-born identical twin has a greater chance of being accepted in a gifted program than the second-born!
There is for sure a genetic component. The correlation is strong enough. 60% of this siblings test within 10 points. That still leaves 40% of them with 11+ difference. 11+ point is a lot. It can easily change HG to MG and MG to non gt.
Either way if one of your children is gt then it makes sense to pay attention to his/her siblings even though they don't exhibit the same gt signs.
Just on this board alone I know of at least two people with 2+ kids in DYS and I am sure I am forgetting somebody.
All that said I do and do not want to have DS4 tested, if that makes any sense. I really hope that DS6 and DS4 will be in the 33% category of siblings with IQ within 5 points of each other.
