Modern phones can analyze a thousand photos per minute. Combine your “Selfies” album with machine learning, and it’s trivial to figure out your age and gender.
It bears repeating, this can be done on your phone. No need to upload photos. Just summarize the interesting details, and upload to the cloud in seconds. And once you grant an app access to your Photos, you really do give it access to all your photos.
Here’s the thing: modern neural nets can recognize objects in real-time.