Do people (family and friends etc.) just let themselves into your house or do you answer the door and let them in?

If they can get through the minefield and sneak past the sentries and avoid the guard dogs, then if they have the correct access code I might let them in.

My daughter and her husband just walk in.
The rest knock.

my parents home is secured by an alarm system...

Nobody except for the people who live here just let themselves in