Kamikaze Midget said:The similarity is a feature, not a bug.
The ARE supposed to be basically the same people, after all, just recently separated in a schismatic conflict.
They've been separated for tens of thousands of years for those of us who've done the math (there've been over 150 githyanki queens reigning in the timeless Astral, including one whose reigned for 1000 years and her predecessor, who ruled for over 500). The illithid city of Oryndoll in Toril is over 12,000 years old, and the Black Spine boxed set sets githzerai and githyanki at the very dawn of psionics on Athas, which was 14,000 long Athasian years ago. It's not at all clear how much of their present appearances is due to illithid alterations of their original human stock and how much is due to subsequent adaptation to their respective planes.
But of course, it's 4e now and all previous continuity is up in the air. But I say it's a bug, not a feature. I like my githyanki more reptilian and my githzerai more catlike, personally.