If the effect is really biological with both eye color and behavior having a common cause (a pleiotropic gene effect), it would be predicted that where one sibling was blue eyed and one brown eyed, that the blue eyed one was more likely to be behaviorally inhibited.
(the effect; is; really biological with both eye color and behavior) (the blue eyed one; to be; behaviorally inhibited) (both eye color and behavior; having; a common cause) (the blue eyed one; was; more likely to be behaviorally inhibited)
the effect the blue eyed one both eye color and behavior the blue eyed one
is to be having was
really biological with both eye color and behavior
behaviorally inhibited
a common cause
more likely to be behaviorally inhibited