Do people realise how insulting it is to claim ‘s/he doesn’t look mixed-race’ and ‘most people won’t realise s/he’s mixed race?’
Because what you’re saying is ‘I have a stereotypical notion of what black people look like in my mind, and Meghan Markle doesn’t fit that stereotype’.
Genuinely don't understand this. When I was growing up we lived next door for a number of years to a Pakistani family. The mother gave birth to a child with incredibly pale skin, freckles and red hair. We knew she was mixed race purely because we knew the family. It was unusual because, given her genes, she was far paler than science tells us she should have been. It made no difference to how we treated her, or her family, because even if she had been born brown skinned our behaviour towards them would have remained as it always had been - mutual respect, friendship, absence of racism/ application of stereotypes. I have little doubt that she suffered less racism when not with her family, because she was not obviously brown skinned.
A stereotypical notion is assuming someone has certain unseen characteristics or behaviours purely on the basis of how they look - I.e. our unconscious bias.
My observation of MM, without knowing her background, was "wow, she's beautiful. Beautiful skin tone, lovely dark hair - she looks like many women I have seen from Spain and Italy". When I discovered her mum is black, I thought: "wow, she's beautiful. Beautiful skin tone, lovely dark hair." The only thing that changes is that I now know she's not Spanish or Italian. It literally makes no difference to how I perceive her knowing that her mum is black. Because I don't attribute stereotypes based on someone's appearance. Had she been 'obviously' black, I would likewise have thought her beautiful. What interests me most is how she is so very untypical of the kind of people the royal family usually couple with: mixed race, feminist, feisty, qualities I admire and respect.
At no point, however, either having knowledge of her background or not, would I have thought to compare her to a monkey. But if I were a racist, then I would have been more likely to use the ape trope having known about her family background, which rather proves how illogical and baseless racism is, but cannot be denied.
MM's 'stereotype' is not about her physical appearance. A stereotype would be assuming that she will behave in a certain way or hold certain beliefs purely because of how she looks and discriminating against them because of it. And that would indeed be racist, when based on the colour of her skin.