How can genetic recombination through segregation and crossing over lead to varation in offspring?

Answer 1

These are the two most important ways that make offspring be different from each other.

1. Independent assortment means that the way one pair of chromosomes separates does not affect the way another pair of chromosomes separates. This means that offspring can get either one of each pair of chromosomes from each parent. Independent assortment makes many, many combinations of chromosomes possible in the offspring.
2. Crossing over happens during prophase I of meiosis I. In crossing over, the neighboring strands of a tetrad (synapsed homologous chromosomes) trade segments. So when the tetrad comes apart, two chromatids will be just like the parental chromosomes, and two chromatids will have new combinations of genes. This causes endless variety in the combinations of the genes in the gametes.

Answer 2

You are getting variation in genes with swapping out parts of the chromosomes. Different variant chromosome are going to the gametes. I wish I could show you in color how the variation of XX crossing over can change your chromosome genetic make-up.