How can it be that most of my photo archive has uploaded to Google photos without me every knowing it? I have no idea how they got there, and no idea how to stop this from happening again. If it helps, I use a MacBook Pro and I keep all my photos in the Photos app (formerly iPhoto). I really need to know what is going on here, as it frightens me to think that personal family images might be floating around the internet.
Google doesn't share your photos with the web automatically. It may have upload them, but they are not automatically shared with anyone. It maybe that you, or another member of the household installed Google Photo backup. Google Photo backup could have come bundled with another product you installed.
You control what is shared and what is not.
As a prolific google photo user, I have 30,000 pictures, and not a single one was shared without me clicking the share button.
For me, it provides a convenient way of backing up my photos in case of fire,flood, theft, hardware failure, and etc.