'F' here. I don't mind sharing, but I do think it shouldn't matter. Perhaps unfortunately, sometimes I do catch myself thinking I might have a different perspective on someone's post if I knew their gender, but in the end I like that none of have the opportunity to judge each other on anything other than our thoughts. And in going back to the original post in this thread, and why the gender issue came up, remember that by knowing someone's gender you do not necessarily know their sexual/relationship preference.
Moderators: if this does get added to Profiles, please be respectful by making it an optional entry.