The triple genesis phase of humans occurs during the last four months of pregnancy. Because this is when your cells are united with your maternal grandmother and mother. Every human goes through this process at least once. Basically if you are a guy you only get to experience this once. But if you are female it all depends. It depends on how many daughters you have.
It is during the last four months of a normal pregnancy that three generations coexist as one organism on a biological level. But only when a mom is pregnant with a girl.
A great example we can pick on is the current US President - Barack H. Obama. In the summer of 1942 his maternal grandmother Madelyn was pregnant with Anne and within Anne was the first cell of Barack. So from about June 29, 1942 until November 29, 1942 Barack H. Obama was in his triplet phase form united in body on a cellular level to his mother and grandmother.
So what? Well it gives Obama an Echo of Biological Memory extending back to the 1800s.