"The entire species, across all the planets it's on...tens of billions, maybe a hundred or two of billions at the high end. Counting relevantly capable hybrids, maybe half again that. Lots of us get any training but not much; enough to, say, ensure that the baby gets, say, the one parent's eyes and the other's height but not much more than that. I'd say...ballpark fifteen percent on the high end, five percent on the low accumulate a decade or two of training over the course of their lives, enough to mostly customize the basic physical attributes of a baby, determine specific ratios of parentage--so that you could, say, collect genes from five donors and ensure that the resulting child is almost entirely the offspring of two of them, with the third's eyes, the fourth's hair and the fifth's brainpower, say. The level of skill my mother has would take a couple of centuries for most people to acquire. My sister and I are as--normal--as we are because she designed us when she was much younger than she was when she died. The Duke commissioned her to design his heir and she managed to cram almost full loads of four or five different species into that kid--Frost giant, halfling, orc, strider and maybe oracle but that one's unsubstantiated, I don't actually know for sure--and the kid still looked almost entirely frost giant. Uh, that's impressive, it's really hard to fit more than about a species and a half's worth of magic in one kid."