Reading vertically the first letters of the mothers', father's and children's names are:
Mothers: J F M A
Fathers: S M T W
Children: M V E M
Each of these patterns fits with the first letters of three different patterns of things.
For example, if one of the patterns were numbers' names then the names would start with O T T F (One, Two, Three, Four)
Once this is known, it's just a matter of recognizing what the three different patterns of things are.