That's really odd. What happens if you put this tag in the content section of a resource that has published children:
[[!getResources? &parents=`[[*id]]` ]]
BTW, there is no default "content TV". For one thing the 'content' field is a resource field (as are pagetitle, description, introtext, etc.), not a TV. TVs are the things in the Template Variables section of the Elements tree that you create. This isn't a criticism, I'm just trying to make sure we understand each other.
More importantly, there are no default fields. No fields will show up unless you put a tag for them somewhere. If the resource's template doesn't have a tag for a resource field, the field won't be shown. For example:
<h3>[[*pagetitle]]</h3>
<div id="content>
[[*content]]
</div>
My apologies if you knew all that already.