Im wondering if differences in things such as ligament size/strength, skeletal structure/shape will play any part in giving any advantage? I cant imagine those can be balanced by hormone therapy if they are a factor?
I think that's pretty much it. Male puberty grants permanent benefits in muscular and skeletal development that female puberty can't give.
You don't undo that by suppressing your testosterone, which is currently the only real requirement for competing.
Couple that with still being allowed higher testosterone levels than ciswomen (including DSD athletes) and having a body equipped to make better use of that testosterone, and I'm not sure there's a way to maintain fairness and have the same inclusivity.
Puberty/hormone blockers can offset it, I think, but as I said earlier, there's a debate around the ethics of these treatments and the long term effects are not yet truly known, but that's not really for this thread.
I imagine if proven safe, there may be a much fairer pathway for transgender athletes, but the "if proven safe" is still being explored. From what I've read, underdeveloped and therefore brittle bones is a side effect they're worried about, as is a lack of mental development that would usually occur during puberty.
The guidelines relating to transgender athletes changed in 2015/16 because they a) didn't want to exclude anyone from a country that wouldn't provide legal recognition of gender identity, and b) didn't want to force people to undertake life changing surgical procedures.
I can understand the thinking there, but the changes meant that the requirements had suddenly gone from needing legal recognition of gender and full reassignment surgery (often accompanied by cross-sex hormones), to living as your gender for 4 years in pronoun use and self-declaration only, and suppression of hormones below a set level for 12 months. It's a drastic step, and the IOC have already acknowledged that the science doesn't support the changes to the guidelines, and this is the first Olympics to truly be affected by them.
I posted an article earlier about this, and the IOC doctor said they need to find a sweet spot between inclusivity and fairness, which is true, but, at the elite level especially, I think the science needs to prove the fairness of the inclusivity, rather than have the inclusivity while they're working out how fair it is. It may well turn out that there is no sweet spot, as such.
Hubbard will be a good case study for this. By the rules as they were, she qualified fairly, but before her event had even come around, the IOC were announcing that those same rules that were allowing her to compete, were not fit for purpose.