The picture ID on my outgoing Mac mail  is not mine -- it's the photo of boyfriend of my mother in law is appearing as my ID photo.  I have no link or connection with anybody  or other accounts whatsoever, and I don't have ANY third-party networks myself.

What version of OS X are you running?

Nobody but you sees that photo, it does not appear on outgoing emails.

To remove the picture rather than change it, open Address Book and select your personal card, then from the menubar select Card > Clear Custom Image. Now the system will use Apple’s generic user picture in the login window and System Preferences’ Accounts pane. Mail and Address Book will remain blank until you designate a new picture in Address Book or System Preferences > Accounts.