Age of first menses has been dropping over the past century and a half. It’s especially notable because the average age of first childbirth has risen in the same period of time.

https://hsph.harvard.edu/news/menstrual-periods-are-arriving-earlier-for-younger-generations-especially-among-racial-minority-and-lower-income-individuals/

My daughter got her period the exact same month as I did. Our birthdays are the same week, and I started at a memorable event, so it was easy to remember.

We were both ~2m shy of 14. My mom was older, 17 and I think my sister was 16/17. They both were likely in significant caloric deficit whereas my daughter and I were athletic/muscular and healthier.

In my experience none of the girls in my family have had their periods at the same age. My older sister got hers at 10, I got mine at 12.5. My mom got hers at 13. My eldest daughter got hers at 14 and my younger daughter got hers days after she turned 12. We all have the same body type.

You get half your genetics from another person. Ask around your Dad's family or your husband's family. Its likely your body type matched your Dad's family and not your mom's hence the earlier period.

Honestly, I think it’s more food, environmental, and body type related. Was your mom pretty thin as a teen? And you thicker? My mother got hers at 14, almost 15. I got mine at 11. But when I look at pictures of her from teen and childhood, she was always very thin and was always toward the heavier end of normal.

I was shocked to learn that my mom did not have first menstrual period till age 17. Why did I get mine at age 10? I am her only daughter. I wonder if there is any correlations or prediction for her granddaughter (i.e. my daughter who is 8 now)? I know there is one for height prediction and pregnancy symptoms, like mother like daughter.