I have a doubt and looking for help. Here is the scenario -

For the Household Account Model, every time I am creating a new contact, Salesforce is creating the Account for me automatically(If not present already). Now adding a new address against the contact and marking it "Default Address", the same address is copied to Contact's Mailing Address field. But the same address is not getting copied to Household Account's Mailing Address field. But to my surprise, the moment I update the Contact's Mailing Address field, the same value is now copied over to Household Account's Mailing Address field. 

My understanding is - "In Household Account Model, contact's Mailing Address will be copied into Household Account's Mailing Address". Please help me in understanding this behavior.