Question

in sexual reproduction, of each chromosome in a pair has the same genes, how is genetic variety possible?

Answer 1

This answer will depend on if you are speaking about asexual reproduction or not.

Variety is possible here because the the product genes are half from the mother and half from the father. So a child might have blue eyes from his mother, but red hair from his father, etc. Different genetic mutations are the initial cause of all differentiation between genes, which are passed down from each generation to the next through this same process.

In Asexual reproduction, all reproductions are essentially clones of the parent, and no genetic variation, other than mutations will occur.

Answer 2

Punnet Squares, they are charts to determine genetic variation by genotype and phenotype :)