Skull Development
The researchers seem to agree that actual skull size makes no difference, because the cause is a mismatch between bone growth and brain growth – the skull stops growing but the brain doesn’t get the message and carries on growing. So it doesn’t matter if the skull grows big before it stops, the brain still doesn’t get the stop message. Something similar happens with many cancers: the gene responsible for cell growth mutates/changes so that it becomes deaf to orders to stop its activity, and just goes on producing cells.