why does my iphone receive other peoples text messages?
my I phone has begun picking up text messages and phonecalls being received by other I phone users in the household.
iPhone 5c, iOS 9.2
Because you are sharing an iCloud account.
Apple has stated that iCloud account are not to be shared because this issue could happen.
https://appleid.apple.com/#!&page=faq
Can I share an Apple ID with someone else?
Your Apple ID should not be shared with anyone else. It provides access to personal information including contacts, photos, device backups, and more. Sharing your Apple ID with someone else means you are giving them access to all your personal content and may lead to confusion over who actually owns the account. To share iTunes & App Store purchases, photos, a calendar, and more with someone else, try Family Sharing, iCloud Photo Sharing, or other easy-to-use sharing features.
Have other sign out of your account and log in with their own.