Our eighth question comes from clodia_risa, who asked...
"How are the bloodlines from the Firsts of the fae passed to their descendents? Did the three have many Firsts (multiple Daoine Sidhe) who bred and created the entire bloodline? Or did the "Firsts" of the different kinds have kids with each other, and each of their kids just happened to be much more like one parent than another? 'Rosey' and 'Pumpkin' definitely have some bloodmixing because of their parentage, despite their mothers being Firsts. Was it a different time? Were the Hope Chests involved? Did The Three have something to do with it?"
Well, first off, "Rosey" (names changed to protect the innocent) is not a Firstborn: she is the daughter of the daughter of a Firstborn. Which is not the same thing at all. "Pumpkin" is the daughter of a Firstborn. Both of them are members of their respective fae races; they don't have the genetic flexibility of Firstborn. Anyone they have children with will be members of their race, and will share the traits of their parents.
"Rosey" is an interesting case, because she's not just a mixed-blood, she's a mix of two types of fae who should never, under normal circumstances, have been able to reproduce. She's probably infertile, at least until something changes. "Pumpkin," on the other hand, is just a changeling. Note that Firstborn + human still = changeling. It's only one of the big Three whose blood is powerful enough to overwhelm any trace of humanity. Their children are always purely fae. There are no changelings among the Firstborn.
That being said, each Firstborn will tend to have children who are of similar, if not identical, races, as long as they stay with a partner who is the same, or at least similar. So a female Firstborn, such as the Luidaeg, would need to stay with the same man/find other men of the same derivation. Six kids with the same second First = six kids of the same fae type. Six kids with different Firsts = six different types of fae. Six kids with random Daoine Sidhe = six kids who are so similar that if their children intermarry, they will become one fae type.
(Yes, there is a lot of generational incest in Faerie. I try not to focus on it, but when you can literally say "100% of us are descended from the same three people," it's inevitable. Most of the time, a few centuries without living as family makes it more palatable.)
The Three have something to do with the Hope Chests, and the Hope Chests were once much more common; remember that Toby thought they were a myth.
Times have changed.