▁brain ▁size . ▁Some ▁studies ▁have ▁tried ▁to ▁explain ▁the ▁relationship ▁between ▁brain ▁size ▁( mean ing ▁volume ) ▁and ▁intelligence , ▁specifically ▁in ▁terms ▁of ▁I Q . ▁In ▁general , ▁it ▁has ▁been ▁found ▁that ▁Full ▁Sc ale ▁I Q ▁and ▁Ver bal ▁I Q ▁have ▁a ▁stronger ▁correlation ▁with ▁brain ▁size ▁than ▁Performance ▁I Q . ▁It ▁is ▁thought ▁by ▁some ▁that ▁grey ▁and ▁white ▁matter ▁specifically ▁relate ▁to ▁different ▁I Q s ▁( gre y ▁matter ▁with ▁Ver bal ▁I Q ▁and ▁white ▁matter ▁with ▁Performance ▁I Q ), ▁but ▁the ▁results ▁have ▁not ▁been ▁consistent . ▁It ▁has ▁been ▁found ▁that ▁within ▁the ▁cor tex , ▁the ▁correlation ▁with ▁I Q ▁was ▁very ▁influenced ▁by ▁the ▁volume ▁of ▁pre front al ▁grey ▁matter . ▁ ▁A ▁ 2 0 0 9 ▁study ▁exam ined ▁int rac ere br al ▁vol um et ric ▁relationships ▁in ▁tw ins . ▁M aking ▁use ▁of ▁high ▁resolution ▁M RI ▁data , ▁they ▁found ▁strong ▁gen etic ▁connections ▁correl ations ▁between ▁c ere br al ▁structures . ▁Specifically , ▁the ▁study ▁suggests ▁that ▁a ▁strong ▁correlation ▁exists ▁between ▁the ▁t issue ▁type ▁or ▁spatial ▁proxim ity ▁and ▁gen es . ▁By ▁exam ining ▁the ▁differences ▁or ▁lack ▁there of ▁between ▁the ▁brain ▁size ▁of ▁tw in ▁children , ▁the ▁research ers ▁drew ▁conclus ions ▁that ▁individuals ▁that ▁share ▁gen es ▁( i . e . ▁tw ins ) ▁will ▁show ▁similar ▁phys i ological ▁brain ▁properties ▁compared ▁to ▁gen et ically -