Answer:
Congress is not very representative of the American population as a whole, because some demographic groups are overrepresented (for example, upper-middle-class white males), while other are underrepresented (for example, lower-class hispanics).
However, this does not necessarily mean that a white person cannot for example represent, a woman, or a minority citizen, or a poor citizen. A white person can understand the problems of these demographic groups, and be a good legislator.
Notwithstanding, it is true that Congress should ideally have a more inclusive representation, where many other demographic groups are represented.