You mean people with genius IQ’s over 140? I am not sure about those with 140–160 IQ’s. Their heads are surely larger than average, but whether you would notice it or not is dubious.
But quite a few super geniuses with IQ’s of 160–200 have extremely large heads. Christopher Langan had to special order a motorcycle helmet made specifically for him because his head was so big. The manufacturer told him that only 1 out of every 3.3 million people had a head as big as his. He has some videos on Youtube. If you look closely at him, you might notice that one thing that is remarkable about him is that he does indeed have a huge head.
This is where the term “egghead” comes from. If you get a chance, look up an old photo of the team that worked at the Manhattan Project to make the nuclear bomb at White Sands, New Mexico. There are 30-40 men in that photo. Look closely at them, and you will see that most of them have pretty big heads. In particular, look at how big their foreheads are. The larger forehead on very bright men gave an egg-shaped appearance to their skulls, which gave rise to the phrase.
