My periods are brutal, but regular. My oldest two daughters (twins) will be 17 in August 1st. They started their periods at age 11, within a few weeks of one another. We aren’t synced to the point that we’re all 3 bleeding and crying and eating anything that remotely looks like chocolate all at the same time, but we are back to back to back. One of us will start and just as we’re ending, the next is starting and just as that one is ending the next is starting. I honestly feel bad for my husband and son… 3 out of 4 weeks of the month, someone in this house is bleeding from their vagina and being kinda bitchy. 
In my family it always depends on who gets their period first every month since we were all pretty irregular but as soon as one girl started wed all follow soon after, 3 sisters and a mom against our youngest brother oof what a nightmare:joy:
I have two girls we are all on different weeks
Me and my mum were always a week apart sometimes I’d get mine first and other times she would get hers first but since I had my kids me and my mum get them completely separated we never know when we get ours untill we get it also my mum gets hers once a week and mine is all over the place I can go 3-4 months with out it and other times I can get it every second week
Mine synced to my daughters. We are off by 1 week right now as I lost a baby in March, but each month I inch closer to hers.
Wait wtf? This is a thing people believe?
I never synched with my mom but I did sync with my friends.
I did not even know such things existed …
Doesn’t matter as long as they get it and not be PREGNANT
My bestfriend lives with me and we get ours either a few days or a week apart.