When giving commands to Siri, you can refer to people by relationship, rather than name. So, if you want to call your mother on your iPhone, you can say “call my mother” instead of something like “call Natasha Jauch-Hoechstetter.” But to do this, you need to introduce Siri to your family. First, make sure you have a “card” in the Contacts app for yourself, and then go into Settings > Contacts, scroll down to find and tap My Info, and select your card so Siri knows who you are. Next, make sure you have a contact card for your mother, and then tell Siri, “Natasha Jauch-Hoechstetter is my mother.” Or, if Siri doesn’t hear you correctly, open Contacts, open your card (not your mother’s!), tap Edit, scroll down, tap “add related name,” tap the default relationship to pick “mother,” tap the info “i” icon, select your mother’s card, and tap Done.
