Peggy ann can't decide whether she is "pretty" or not. she thinks she may be, but she isn't sure. she decides to observe her friends’ reactions to her in order to determine whether she is pretty or not. she then notices that they all behave toward her as one would toward a person who is "pretty." this illustrates:

Looking-glass self

Explanation:

Looking-glass self is defined as the theory in which as person tends to know about their characteristics and concept of self through the help of reactions gained by others. This concept develops the knowledge about self through other people.

According to the question, Peggy is using looking glass self mechanism for knowing about herself .Se is taking the reactions about herself being pretty or not from her friends.She gets the result as being pretty according to their review.  

answer; genetics;