Break the ice with Siri and let her into your life by assigning nicknames to your contacts. You can do this in one of two ways: vocally or manually. For example, after firing up Siri, you can tell her “John Doe is my father” and she’ll respond, “Okay, do you want me to remember that John Doe is your father?” With a confirmation, you’ll be able to say “Call Dad” and get linked to John Doe’s phone number.
If you want to store a number of relationships at once, go into your own contact page, tap Edit and scroll down to the line that reads Mother. By tapping Mother, you can change to a wide array of options including father, brother, child/parent, friend, partner/spouse, assistant, manager, or even add a custom label.