if I restore from my cousins backup would it change my iOS?

Question

Both my cousin and I have backups on my PC and we both have the iPhone 4. However, she has Sprint and iOS 5.1.1 and I have AT&T and 6.0.1.

Could I use her backup to downgrade my iPhone to iOS 5.1.1?

Answer 1

No. The back up does not contain the operating system.

Answer 2

Unfortunately the backup files only contain personal data, and don't store the iOS version. Apple makes very difficult, if not impossible, in some cases, to downgrade iOS versions.

Here is some additional information from Apple regarding information that iTunes backs up.

iTunes can back up your settings, Messages, Camera Roll, documents, saved games, and other data. Backups do not contain content synced to the device, such as movies, music, podcasts, and apps.