OurBlanche if you're not an expert on chromosomes and sex determination, what relevant issues are you an expert on? Firstly, why does anyone here need to be an expert? But to answer your question, I am part way through a DPhil looking at the effects of strength training on pre/post menstrual women. I have spent 20+ years working with people with sub clinical issues in a wide range of interventions, some of which I am published on. I have taught at FE and HE on exercise and public health, spoken on symposiums about exercise, health, obesity, etc.
What is your expertise on chromosomes and sex determination?
I'd strongly recommend that you (and a lot of the other posters on this thread...) go away and do some research on the history of sex determination in athletics before pontificating. Mmm! Yes, that's a thing I have never thought of... no, wait!
IMHO the article I recommended previously would be a reasonable starting point ( A brief history of intersex athletes in sport). This is a really difficult, complex issue and arguements based on ill-informed opinions won't help solve it. Your opinion! Whilst LetsRun is a good informal source of information, I won't be referencing them at any time soon. I have, however, read and referenced some of Joanna Harper's academic work, have you?
Are such magazines what you base your opinion on?
(IMHO...) Preventing athletes who are XY and have androgen insensitivity syndrome (AIS) from competing as women is probably not fair, since they don't benefit from their high levels of testosterone. On the other hand letting anyone who is XY but dosn't have AIS compete as a woman isn't fair on the vast majority of women with significantly lower testosterone levels. The 2011-15 rule, with an upper limit on testosterone set at the lower end of the normal range for men, wasn't ideal (since there was no scientific basis for the exact level of the upper limit). However it was a better interim measure than the current situation. Yes! All of which I, and many others, said a lot of pages ago... with links, explanations etc.
But tell me, what expertise do you base your opinions on?