That when you live with women your cycle's start to come around the same time. When I was living with my roomates one of them told me her cycle drew back three weeks, I think eventually, and starting coming at the same time as mine. And now I've moved back in with my mom and my period has drawn back a week and a half, not eventual to coincide with hers. My mom had three sisters and her mom and she said there's was always on at the same time. Same with my roomate. I wonder if other people have experienced this?