Hi CH,
I can tell you in my experiences, the people that give dissapproving looks or negative reactions are usually controlling people themselves.
As I have progressed over the years from a distant relationship with my family to a non-relationship, I have noticed the kind of personalities that respond with different reactions. The people who are self-assured, respectful, considerate, etc. appear to accept my response of "we have no relationship" and say things like "I'm sure you have a very good reason for your distance from your family and I will not pry".
But those who like to tell others how to live their lives are the ones that attempt to snoop to find out why, how, who's responsible, and then judge me. I just stop saying things to those who come across in a controling fashion. Actually I may even say very mean things just to get their goat.
My H's brother's MIL is very controlling. At a Thanksgiving dinner last year with H's family, who is very normal, the MIL of my BIL asked about my parents, asking when I saw them last, how are they, how are we getting along - like it's any of her business. To keep things light, but express my disapproval of her asking I said "I don't talk to them, care about them, hell, I know nothing about them anymore and don't want to talk about it". Her expression was complete surprise. I guess she thought I should respect her more than to say a thing like that. She tried to pry and I just turned and started talking to my MIL, laughing and completely ignoring this busy-body. It felt good, I didn't get drawn into an uncomfortable conversation, refused to let her ruin my Thanksgiving by bringing up my family and felt good about it all.
It has taken years to get to this though. In the beginning of all of this, I easily got drawn into explaining everything and in the end, if the person prying was of an N personality, they ended up making me feel as bad as my own family. You eventually learn to pick them out quickly and shut them down before they can get to you. The world is full of controlling people.