"The nature of some data may also surprise. App developers receive your age and gender whenever an app is launched, the study found."
And the accuracy of that age value is not high (I assume age would be from someone having a google account .. but nobody with any sense should use their real DOB when registering with gmail, fb, twitter etc. as DOB is one of the key identity theft targets*)
I assume "gender" found in same way? (presumably with lots of different options these days for covering gender fluidity)
..* and yes, that means you (& friends & relatives) not plastering birthday photos across social media - no point hiding DOB if there's photos of you celebrating 21st birthday (or whatever that also gives year as well as day / month)
Being "camera shy" is handy in these days of social media overshare