macports owns my user folder in most of my backups

[Lenore Horner]

I use Time Machine to backup my hard drive to an external drive.  At some point 
(and I don’t know when) MacPorts became the owner of my folder in Users for 
most or all of my backups.  Folders above that level are owned by the system.  
sudo chown will not change those permissions (the response is operation not 
permitted).  Is there any way to fix this or are these backups useless?
Thanks,
Lenore