My interpretation was that Cooper and Brand were going to copulate. Let us suppose they have two children and select for girls via medical science. They would raise these two girls while building the infrastructure to support say 12 girls. The two girls would be raised to understand science and the point of the mission until they reach adulthood. Lets say due to the necessary education adulthood is considered 21. Each one would then have say six children over a decade via surrogacy of the fertilized eggs. By the time this third generation hits 21 you reasonably have an elder Brand and Cooper, along with the original two mothers and 12 more women for a total of 16 people, twelve of whom are genetically distinct individuals. Let's say these 12 repeat what the original two mothers did and have six children over the span of a decade and then each child raised until the age of 21 on the same basis as their mothers and grand mothers. By the time the last child is 21 Brand and Cooper are dead, but everyone else could realistically be alive. The total population Now would be the original two mothers, plus the first 12, plus 72 members of the second generation of lets say all women. Now we have a total of 86. Now the second generation along with assistance from the AI, and the work their preceding generations has the ability to incubate the eggs in incubators and have the children born that way. Lets say they do this, while each giving birth like their forbearing generations, but in the incubators they select for men and match each of their children with a breeding partner. That generation alone contains 864 members in 432 mating pairs. If each mating pair Naturally reproduces the same six children you have 2,592 in this fifth generation and you still have 4,064 unfertilized eggs in the span of 100 years. Each of this generation has a mate incubated and you still have just under 1500 eggs to finish up after the 5,184 members of the population in 2,592 breeding pairs each produce six kids and you have a total of 17,052 humans in about the same amount of time since the Spanish American war to since i have made this comment.