You have 23 pairs of chromosomes, but don't forget that none of these is exactly the chromosome that any of your ancestors (including ma nad pa) had. During meiosis* (the process of separating the paired chromosomes into the single strands that produce the contestants in the egg-and-sperm race), not only do each of the separated chromosomes distribute randomly into the gametes, but during meiosis the paired chromosomes swap sections with each other, producing a new selection of genes on each one. The process is not completely random - there are preferred sites for the crossing- but it does mean that the genetic material gets a thorough shuffling over time.

*I had difficulty remembering which cell division process was which, until a friend told me: meiosis is what happens in my ovaries. Mitosis is what happens in my toeses.