I've written about this. It's something I have. It drives my kids wild. I don't recognise actors at all, but I can recognise their voices. If I see a photo of my kids on Facebook with other people, I'll have difficulty in recognising my own child! I use other visual clues like what are they wearing or their height to help ( my youngest son is 6 foot 7) As far as I'm aware nothing physically traumatic has ever happened to me. I've always been like this. https://medium.com/the-random-nerdiness-collective/face-blindness-cf373ac9ef04