I am the same way - always a stone face because I am afraid or unable to react. I think the best rule is to try to smile all of the time except when it is inappropriate to do so. Like yourself, I had a stone mother. Never hugged me. Never asked how I was. Never wanted to know what was going on in my life. The effect on my has been dreadful - I am an unhappy person. I am so joyless in social situations.

I have never found a cure despite years of psychotherapy. I did not have good results from CBT. If you find a therapy that helps, please let me know. All the best to you.