Bearing in mind that people learn new things all the time, I'm pretty sure that it would take about 5 seconds for an averagely intelligent person to learn XX and XY (or any other non-stereotyping symbols).
Yes, exactly.
Why should we have those outdated pictures of women in dresses when a new sign could be learnt in 5 seconds?
Also, in the UK most people are going to know which chromosomes are which (if they don't actively refuse to remember).
I suggest we show the y chromosome in its real size, which is much smaller than the X, that makes them easier to differentiate AND is factually accurate, too!
People who don't know can be taught by it being on the same sign as some other symbols, or by just following everyone else.
I didn't use to mind the woman in a dress thing, but it seems to confuse so many people about the facts according to which the toilets are separated, so I think it is time it was changed.