any two full siblings will, on average, share 50% of their DNA. they each inherited 50% of each parent's DNA, but between siblings it will not be the same 50%.

This means that if the parents have enough offspring, their full genomes would be represented in the DNA of their brood.

My question is, how does one model the probabilistic propagation of the parents' genes? my guess is:

proportion of genome passed on = 1 - 0.5^n

where n is the number of offspring.

so with 4 kids 93.75% of each parent's genome would be passed on. of course sorting out what came from who would be a whole can of worms.