I lost my mum when I was 3 in the 80s, I don't remember much about my childhood at all (though I have an extremely vivid memory of one of my uncles lifting me up to look at my mum inside the coffin at the funeral, and looking around and seeing my dad and all my uncles crying).
My family never really spoke about her at all, and as I got older it was hard to ask anything. Occasionally one of my extended family might say something like "oh you're a jack of all trades just like your mum was" or "wow with your hair like that you look just like her" and at events (usually funerals) some distant family friends might talk about her... but my dad has rarely ever mentioned her. I also find it hard to talk about her with my siblings as there is this awkwardness around it that we've all grown up with, I don't even know what to call her - similar to others on this thread too.
As I've grown older I've had suspicions that my lack of any childhood memories was because somehow my brain has just blocked everything out. I think it's somehow helped to protect me as I'm an emotionally strong person now, which is good and bad as I just block out all emotion really - my sisters and husband call me a robot.
My older sister on the other hand (she was 5) remembers so much childhood stuff but also she's a really fucked up adult, lots of attachment and relationship issues. I do think it's because our mum died when she was that little bit older and I've tried to get her to go for therapy in general for her issues as I think they'll explore this too.
My DD is now around the same age I was when my mum died and I've started to think about it often as I'm terrified of dying and leaving her and her little brother without a mum. If I found out I had terminal cancer (which is how my mum died) I would make lots of videos talking to them and telling them how much I love them and teaching them how to be good adults and I would also instruct DH to speak about me to them all time.
I rarely ever cry in front of people about anything, but every now and then, even at the age of 39 if I think about it and wonder about what life would have been like with a loving mother figure, I have a good old sob about what I lost and never got the chance to experience.
Sorry for the essay - it's just good to finally be able to say all this to people who understand, I thought it was just our family (my dad) that was weird but seems like it is (was) the done thing, maybe the adults in the situation thought they were protecting us by not talking about it or maybe they were simply protecting themselves as it was all too painful.