[danwills]

Gamete cells get a random half of all genes from each parent so there's about 2 unique possible 'sets' from each parent, and 2*2=4. However because it's random I think you can only say there are 4 distinct completely unique possibilities in theory, but it would be very unlikely for that to actually happen in practice.

[diroussel]

Each parent supplies half the genetic material. But each sperm and each egg have a randomly different set of one half of each chromosomes. So if you have 10 children chances are they each have a unique set of chromosomes.

[darkerside]

Ahh, as in fully exclusive sets of genes