". A cat as your picture, a fake name or "undefined" as sex, won't contribute to this. "
Er, what? One of my closest friends is better known by her pseudonym, has a rabbit as her icon, and is doing just fine, thanks; we met because of her online reputation.
There are a lot of different online communities. Don't assume that the customs of your community are universal. Wikipedia has been functioning successfully as a pseudonym-only space for a very long time. People's reputations are based on their community contribution, not on their real names.
I refer you to this post of mine for an example of what can happen when you make your sex guessable online. See also World of Warcraft, which had an uproar when people insisted on de-anonymizing the forums, precisely because women feared being stalked. https://plus.google.com/104600580124930283388/posts/YxRNw9XitY2