Here is a quote from
Hoagies Gifted Education Page:
There are a few critical issues that make a whole-grade acceleration not recommended : sibling in the same grade, or sibling in the receiving grade. According to the scales, these are critical items, and totally negate the idea of whole-grade acceleration. I disagree there - in my opinion we should always treat our kids as individuals, and though a lot more care needs to be taken, these two issues should not make whole-grade acceleration a total "NO".
FWIW, I have twins in separate grades. It was recommended back in elementary school (even though they used the IAS), but we didn't do it until the boys were in middle school because we worried about their relationship (among other issues).
My 2E boy with dyslexia is now doing exceptionally well in the grade he's "supposed" to be in. His twin brother has been frustrated for years at being with age peers, and we home schooled last year then skipped him this year (he's making all As!) It's still not a perfect academic fit for him, but he's much more engaged in school this year.
Neither boy has an issue with the skip, and they're very supportive of each other's success. In fact, my 2E boy seems pretty proud of his brother for being brave enough to skip. They key for us is that they are in different schools. My skipper went to an entirely different school in a different district where there are many skippers. So the boys are free to make friends who don't realize they're twins.
We would not (and didn't) make this choice when they were younger, and when my 2E boy was struggling with dyslexia. It would have been a huge blow to his psyche if his brother had jumped ahead then. But now, he's very confident in his abilities and is nearly a straight-A student (B only in writing) and doesn't feel threatened by his outlier brother because he has his own areas where he's exceptional.
If I were making the choice for siblings who were not twins, the issues I would weigh would be their relationship and the level of frustration for the potential skipper. If both kids are truly fine with the skip, I don't see why the school should have an opinion about it.
