Notes on Chapter 3.
Chromosomes mostly come in pairs like a pair of strings of beads of the same length.
At meiosis one string is formed and passed to the offspring. It's as though the pairs of string where cut up at 1 - 4 random places and a two new single strings assembled from the pieces. The offspring gets one of the strings at random. They are linked. The cutting appears almost at random so the probability the two beads are passed together is related to the distance between the beads.