In the legislatures of two different countries there are two very different gender balances. In one of them there are only men. In the other it's half and half men and women. Which legislature would you expect to be more attuned to the interests of women? Dumb question. In a certain university the governing body is composed exclusively of senior professors. Some junior lecturers feel aggrieved that their needs and concerns are not getting enough attention. They press for - among other measures - securing junior-lecturer representation on the university governing body. A preposterous demand? Dumb question.
On the grounds that, for example, a doctor can cure me of an illness he or she hasn't had, and 'posh MPs can serve working class interests', Chris stumbles towards the idea that being representative, in a social sense, of those one represents politically is unimportant. This is not a defensible claim.
True, 'representing' someone can mean different things. Representing people as their MP, you should, among other things, pay attention to both their preferences and their interests while trying to make the best judgements you can regarding policy. Or I can represent you somewhere where you are unable to speak for yourself, and try to speak on your behalf, knowing what you would want me to say. Or a person can represent other persons by being of the same social, gender, professional (or what have you) background as they are: a worker speaking for other workers, a woman for other women, a teacher... etc.
Because it can happen that a woman makes good decisions for the men she represents, and a rich man likewise for people much worse off than himself; and because it can also happen that a person from the very same group or stratum as those she represents can make very bad decisions for them, even 'selling them out'; these are not reasons for denying the old truth that one of the things individuals are moved by is their interests. Representatives do not escape this generalization, at least statistically. You may want to vote for a particular aristocrat, and I may want to vote for a particular aristocrat; but I wouldn't want be governed exclusively by aristocrats.