Why does 'crossing over' only occur in meiosis?

As for why it does occur on the rare times it does, I am not certain as of the time of writing this. Reference: The Biology ... The mechanism is straightforward: in Metaphase I of Meiosis, chromosomes line up in two lines, with homologous across from each other, which allows them to interact by crossing over. read more

Crossing-over occurs during prophase 1 of Meiosis 1. In this stage of meiosis homologous form a chiasmata or an intersection point between them. After the formation of chiasmatas at different points, they exchange chromosomal segments with each other. read more

Crossing over occurs in meiosis to create diversity in the genetic material so the offspring is neither identical to father or mother. in mitosis it does not occur because the parent cell is making an identical copy of itself, so the DNA does not need to vary. read more