Dress Sizes Bmi If A Woman Is A "perfect" Size 36-24-36 (90-60-90), Then What Dress Size Would She Wear (US Dress Size)?

If a woman is a "perfect" size 36-24-36 (90-60-90), then what dress size would she wear (US dress size)? - dress sizes bmi

This is a 4? 6? 8? 10? 12? Etc?

I also found some female figures with measurements of 36-24-36, however, all the clothes in different sizes, such as:
Ana Hickmann (is) Brazilian model a size 6
Supermodels Elle Macpherson and Nadja Auermann are size 8
The legendary Marilyn Monroe was a size 14
Halle Berry is a size 2, if I mistake not,

How could this happen? Howcome they all wear clothes in various sizes, if you have similar action?

If the size of the dress, is determined solely by their actions? Or are there other factors that influence and the weight and height, BMI, Bra / cup size, proportions, body shape, etc.?