The parent's paternal and maternal chromosomes recombine to produce the corresponding chromosome in the egg or sperm:

Paternal: gtacgatcgtagatcgatcatatccgtacgcatcatgactacatatcatcgatcgatcatcatatcgatcatcagcatcgatcgatcgatcgatcgat
Maternal: gggggggggggggggaccagtatgtatcagtcctattactacatctactataactatctactagctagcaatatcctactcatacatctacttactgt

Combined: gtacgatcgtagatcgatcatatctatcagtcctattactacatctactataacgatcatcatatcgatcatcacctactcatacatctacttactgt

In practice, cross-overs are much less frequent than in this stylised example.

Cross-over locations are different for every sperm produced by a man and for every egg produced by a woman.