I think you can actually get a pop going with a single breeding pair, because I think the incest restriction is restricted to siblings, in which case the first generation offspring would be able to marry second generation ones
Well, the problem with that would be the age gaps. In version 44 and older there is a strict maximum age gap of 10 years and for this reason you really needed two pairs. In the latest version it *might* work, but I don't know the exact way it handles age gaps now. Then again, in the latest version it should be much easier to get babies from different parents in any case, now that we no longer have strict monogamy and dwarves don't even have to be married to get kids.
I must be mushy in the head! You generally need two pairs to get two kids of the first generation to be able to produce second generation offspring to get the process started.
I agree that the kids produced by the first pair MIGHT eventually reach an age where they're allowed to marry one of the starting 7 (other of the parents, of course), but it will take a long time, and there's a significant risk the potential spouses would die of old age before that (and fortress building will be slow for the 60 or so years before kids produced by a first generation kid mature).
The age gap rules as described by Toady a bit over a year ago are fairly simple:
- A civilized creature may marry one who's +/- 10 years of their own age, assuming both parties are adult (i.e. 12 years in vanilla).
- The older party may be at most half again the younger party's age when that's at least 10 years. Again, they have to be adult.
Thus, a fresh adult may marry a 22 year oldtimer. At 20 the rules break even, setting the limit to 30, while at 50 it's 75, at 400 it's 600, etc.