<html><head></head><body>I agree with the previous posters. 25 kids is more than enough to make most of the genome likely to be preserved in the next generation.<br><br>...but then there is the second generation. If every generation has 25 kids, fine. (The family reunion may require a major convention city, though).<br><br>We can work backward: between you and your ancestor there are N generations. Each generation implies 50% chance of a change in gene. So for a given gene there is just 2^-N chance that it is the same. If there are D descendants, the chance that at least one has the original gene is 1-(1-2^-N)^D. If there are K genes, then the chance that there is at least one copy of each gene among the descendants is (1-(1-2^-N)^D)^K (phew). <br><br>Now, that probability declines fast as K increases but is counteracted by D. If you plot the probability as a function of D you will see a sigmoid curve. If you have N=4 and just look for one gene, you need 11 decendants to have 50+% chance of getting it, and 72 to get 99% certainty. For 10 genes, you need 42 descendants for 50% chance and 107 for 99%. For 1000 genes you need 178 descendants for 99%. For 20,000 genes you need 224 descendants. <br><br>Wow, that was way smaller than I thought! (of course, I could have messed up the math) <br><br>However, as N increases the population needed grows fast (it is after all in the innermost parenthesis). For N=5 you need 457 descendants, N=6 920, N=7 1849, N=8 3705... the number of descendants you need doubles per generation back to the ancestor. <br><br><br><br>Anders Sandberg,
Future of Humanity Institute
Philosophy Faculty of Oxford University</body></html>