Please note, that in Harry Potter, to my knowledge, J K Rowling has not written about or included any lesbians, drug users, singers, alcoholics, one legged Peruvians, Russians, people in to dogging, unemployed people, or even glamour models.
Gay friends of mine have never thought it funny that there is no gay character in the Harry Potter stories either, so quite why we should have to worry about it, heaven knows !
Update : For the record, Harry Potter also includes no traffic wardens, car mechanics, sun worshippers, Jamaicans, Inuits, or even Leeds City Councillors. Although now having mentioned Leeds City Councillors, David Morton (sorry, Councillor David Morton) will now accuse me of being Leedsist or a Councillorphobe. Well, perhaps not accuse, but he will drop strong hints that that is his view.