Who determines an individual's identity? Does an individual chose an identity as a member of a particular group or is their identity assigned to them on the bases of observable characteristics? Who decides what characteristics determine membership in a particular identity group? The individuals who chose that identity, or those who don't?
This is a problem in studying any human behavior. What is the difference between having a characteristic and identifying as a member of a group of people who have that characteristic?
A person can have a characteristic and not identify as a member of the group of people having that characteristic. (i.e. someone with a drinking problem who doesn't think they are an alcoholic). A person can identify as a member of a group of people having a characteristic and not have that characteristic. (i.e. people of European decent who think they are Native Americans).
Generally when we speak of a person's identity we mean either 1) who they think they are or 2) who we think they are. This involves many issues including the nature of truth, validity claims, and definitions. It is obvious that people with different boundaries on their identifying characteristics will come to different conclusions about who qualifies as a member of a group. That is clearly a problem of definition. Any claims to validity must be based on the definitions being used. (i.e. does the person in questions have the characteristics to meet the definition.) If there is not agreement on the definition there can be no agreement on validity of claims. If there is no agreement on validity there can be no agreement on the truth of claims.
For the purposes of this discussion attribute membership is defined as "membership assigned by observed characteristics independent of assertions of identity". Possession of a characteristic is no guarantee that an individual will recognize themselves as a member of the group of people sharing the characteristic. Even if membership is offered it is not necessarily sought or accepted. The sole criteria for attribute membership is the observation that the individual has the characteristics to meet the stated definition.
Identity does not guarantee Attribute.
Attribute does not guarantee Identity.
Our definition of the world around us are based on our experience of it. Part of that experience is what we see and hear from other people. We either define the characteristics necessary for group membership and identify people accordingly or we accept self proclaimed group membership and define the group by the observable characteristics. We base our decisions about ourselves and others on our internal definitions acquired through experience and internalization.