In the question below, a sentence is given with two words missing. You are given five options each containing a pair of words that can or cannot be filled in the blanks to make the sentence contextually and grammatically correct. Identify the words that are similar in meaning and make the sentence contextually and grammatically correct. But since ______ and ______ are formative for us, and yet we can explicitly remember little about them, we are left in the dark about fundamental features of our own personalities.