Your age doesn't let you know when you're old your body does, agree? I heard women having menopause in their 20s and 30s and women in their 50s and

I disagree - age is inherantly a function of time. How your body ages is a different matter and everyone is different. Typically we see patterns but as with most things there are outliers, genetics plays a large part - e.g. signs of aging in females such as loss of skin elasticity aren't the same for every adult female - e.g. those with african heritage don't seem to undergo this transformation until a later age compared to those from northern europe.