Sure, let the show begin!
Start by setting the first Custom Field to "Gender" (Control Panel, Registration Settings) and make it an Optional/Required field.
Now, let's open up public_edit_profile and find:
[/code]Replace with:
</pre></div></div>Next, open public_topic_page.pl and find:<br><div class="ubbcode-block"><div class="ubbcode-header">Code</div><div class="ubbcode-body ubbcode-pre" ><pre>
Replace with:
[code]
You're done!
Note this is for the regular templates, not JCTemplates.