diff --git a/project_directory/common/models.py b/project_directory/common/models.py
index be9cc1a..018c8f7 100644
--- a/project_directory/common/models.py
+++ b/project_directory/common/models.py
@@ -14,7 +14,8 @@ class CommonInfo(models.Model):
 
 class Category(CommonInfo):
     parent = models.ForeignKey('self', blank=True, null=True,
-                               on_delete=models.SET_NULL)
+                               on_delete=models.SET_NULL,
+                               related_name='children')
 
 
 class Sample(CommonInfo):