There tend to be a lot of single dwarves, with 3-4 mega families. Mothers with 20+ children. Everyone else is all single and friendless. However these queen dwarves reproduce so quickly that any dip under the child limit instantly causes all of the 3-4 mega moms to become pregnant again. I use a low child limit of 25. However like all limits in the game its not absolute, and so if there are 24 children all 3-4 megamoms can get pregnant at the same time, resulting in 27-28 children a few seasons later. Then the children grow up to become spearcatchers, and more babies are born.
This has an interesting effect with the military though. As I recruit peasants into my military this means that almost all soldiers are related to each other. Military tantrums are more common, as a single death will cause much unhappiness as that dead dwarf is related to a dozen other dwarves in the military. This is why I put cage traps around each bottleneck in my fortress. Any berserk dwarves are very quickly captured in cages, then hauled to a stockpile where they slowly die of starvation in their tiny cage. Once dead the remains are hauled to a butcher workshop for a final humiliation, then the pieces put into a coffin.
For some reason they will butcher dwarves who die in cages, yet they will not eat the dwarf.
Elves? The butchers and cooks are all over those! But not dwarves.