[cosmie]

I agree that it'd be nice to know which data point was used for audience building.

   > I use a different email, different name, no phone number, no address on FB... I don't get it.

Not sure if phone number can be used for audience targeting (it's not available to self-service, normal advertisers iirc). But wanted to clarify this part. Just because you haven't added it in no way means that Facebook doesn't have your phone number. Or your alternate name. Or your different email address. With the way that the Facebook app syncs to most people's phones, all it'd take is one person associating your Facebook account with their phone contact of you for Facebook to start associating those alternative contact/data points with your Facebook profile.

[mirkules]

Interesting. Now that I think of it, for the last few months FB has been relentlessly trying to get me to associate my phone number with my account - and they even display it in Firefox (which was surprising that a browser could pull a phone number). After what you said, I wouldn't be surprised if they associated it anyway.