 This corroborated studies that have shown that brain growth in the brightest children, and children with autism, increases after birth and peaks at around age 11 or 12 before slowing down in adulthood.In the second group, birth head circumference was not found to significantly affect IQ, further corroborating these studies.The second cohort had previously had a genetic analysis rule out any effect on IQ of other genome-wide copy number variations they had, further suggesting a critical period of activity of CON1 and CON2.