org-show-siblings

org-show-siblings is a variable defined in `org.el'.
Its value is

((default) (isearch t) (bookmark-jump t))

Documentation:
Non-nil means show all sibling heading when revealing a location.
Org-mode often shows locations in an org-mode file which might have
been invisible before. When this is set, the sibling of the current entry
heading are all made visible. If `org-show-hierarchy-above' is t,
the same happens on each level of the hierarchy above the current entry.

By default this is on for the isearch context, off for all other contexts.
Turning this off for example for sparse trees makes them very compact,
but makes it harder to edit the location of the match. In such a case,
use the command M-x org-reveal to show more context.
Instead of t, this can also be an alist specifying this option for different
contexts. See `org-show-hierarchy-above' for valid contexts.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 24.4 of Emacs.