By default the genres custom field is only enabled for musicians. The Musicians user group is nearly an add-on so it has its restrictions.
Some administrators may decide to allow non musicians to upload music so it makes sense to have genres in a user's profile.
The way we will describe here is not a perfect fix but serves the purpose.
1. Go to the AdminCP -> Extensions -> Theme -> Manage Theme http://i50.tinypic.com/15fliky.png
2. Click on the arrow and Edit Templates http://i47.tinypic.com/2925zd0.png
3. look for the Music module and the genre.html.php block http://i49.tinypic.com/4greqw.png
4. Replace the text with this one:
{for $i = 1; $i <= $iGenerCount; $i++}
<div class="{if PHPFOX_IS_AJAX && !$bIsGlobalEdit}info{else}table{/if} js_custom_group_{$iCustomGroupId}">
<div class="{if PHPFOX_IS_AJAX && !$bIsGlobalEdit}info{else}table{/if}_left">
{phrase var='music.genre_total' total=$i}:
</div>
<div class="{if PHPFOX_IS_AJAX && !$bIsGlobalEdit}info{else}table{/if}_right">
<select name="custom[music_genre][{$i}]">
<option value="">{phrase var='music.none'}</option>
{foreach from=$aGenres item=aGenre}
<option value="{$aGenre.genre_id}"{if isset($aUserGenres[$i]) && $aUserGenres[$i].genre_id == $aGenre.genre_id} selected="selected"{/if}>{$aGenre.name|convert|clean}</option>
{/foreach}
</select>
</div>
</div>
{/for}
This will show the Genres in every tab of the Edit Profile section.
We do have plans for including a full fix but meanwhile this will hopefully help.