When speaking Siri commands, you can refer to people by relationship, rather than name. So, if you want to call your mother, you can say “call my mother” instead of saying 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 > Mail, Contacts, Calendars, scroll down to find and tap My Info, and select your card. 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, edit your card (not your mother’s!), 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.
– ASMC TidBITS Content