I think a lot of the "magic" ratios and "gender" markers are just a convenient excuse for our differences. Some trans people feel more comfortable if they can "prove" they are physically different. If you feel more socially acceptable because your finger ratio is just so or any other body parts then good for you. As long as it isn't used as a test (trannier-than-thou) then who cares.
My index fingers are marginally longer and my second toe is smaller than my big toe (another "marker" people use), but I could likely find a dozen "tests" that would show maleness instead. However my CIS-female wife's second toe is bigger than her big toe which is "supposed" to be a marker for maleness.
It is all so variable and there are so many interacting factors that it is never going to be that simple. As some people said hereditary plays a huge role in some of this, but then sometimes some of our characteristics don't fit that mold properly. For example even though I am 5'11", I was always considered short by my family. Standing next to my 5'4" wife, our hips are at the same height so my legs are short, but then I have a long torso so even parts of my body fit the hereditary profile of that family while others don't.