Comparing ourselves to other girls is quite common amongst women. It's part of the personal verses social identity continuum where we can perceive ourselves differently at any given moment dependent on where we are on this objective scale. Think of it as intragroup comparisons where we compare ourselves with other people whom share our group membership (i.e. being female). Not only must gender [sex] be salient for gender [sex] differences in self-construal to emerge, but recent research has also shown that how we perceive ourselves depends mostly on whether we are comparing ourselves to the same gender [sex] or a different gender [sex]. In many cases our comparison to other women is done out of envy where we see something that another girl has and we want it (e.g. having small breasts and seeing girls with big boobs) we then tend to focus or fixate on that "thing" and compare it to ourselves, but one have to be careful because in doing so it can lead to self-depreciating behaviors (e.g. I won't ever get big boobs, it's because I was not born biologically female, I look stupid).
In a lot of cases we are doing an upward social comparison where we compare ourselves to people we perceive4 to be better or superior to us and find reasons to sort of degrade them in favor of ourselves. I think this is more prevalent in transsexual women because of our heightened self-evaluation maintenance model. Thus, in order to try and keep a positive view of ourselves we tend to distance ourselves from other people who perform better than we do on valued dimensions (e.g. pre-operative transsexual girls being sarcastic to those of us that have had SRS causing us to be a sort of social pariah in the transgender group) and move closer to others who perform worse than us like when post-operative transsexual women sort of takes a new transsexual girl "under her wings." This works both ways between between the two minimal groups.
