My story, set in 1990, has secret societies of immortal beings (vampires, werewolves, elves, leprechauns, etc.) living amongst the human race and trying to survive while remaining a secret. One idea about this world that I've had for ages is the concept of "grades" of magical blood, both in the immortal beings and in the human stock they mutated from. There are four grades, in increasing order of power and rarity: gamma (60% of the human population), beta (30%), alpha (9%) and cambion (1%). The higher your grade of magical blood, the more of your race's powers and the fewer of your race's weaknesses that you have. If you're a human, your blood grade is randomized at birth, basically completely irrespective of what grades your parents were. However, if you're an immortal, the grades of your parents are taken into account, and due to how it works, it'll most likely be the lower grade between the two. For example, a cambion immortal with an alpha partner has a 1 in 10 chance of having a cambion child, with a beta partner it's 1 in 31, and with a gamma partner it's 1 in 61. In addition, in cases where it's an immortal and a human, if the human is the one with the higher blood grade, it will automatically default to the immortal's lower grade.
This means that the cambion immortals are rare and, crucially, impossible to replace should all of them be destroyed. This has caused immortal species whose cultures emphasize protecting the cambions among their ranks to have a survival advantage, meaning most immortal societies regard cambion life as far more valuable than the lives of lesser blood grades. The way I envision it currently, the culture many immortals are brought up in drives most lower-grade immortals to be prepared to die to protect the cambions among them. A "lowblood" who allowed a cambion to die to save their own skin is regarded in nearly all immortal circles with the same visceral contempt with which a human would regard someone using an infant as a human shield.
Now, obviously, I know enough about history to know that it's far from impossible to make people prepared to die in the name of something they perceive as greater than themselves. The issue comes with species like vampires.
See, vampires, like in nearly all popular culture, have the ability to "turn" humans into more vampires. A vampire can't turn a human of an equal or higher magic grade than themselves, so this isn't a way to make more cambions, but it allows them to replenish their ranks extremely quickly as long as the cambions stay alive, and it's a major survival advantage that has caused vampires, along with other races with the ability to "turn", to become the dominant immortal species.
But this means that vampires will regularly be replenishing their ranks with ex-humans who grew to adulthood in a completely different culture that didn't drill into their heads how important it is to keep the species alive at any cost. The entire survival advantage of these turned vampires is the ease with which they can be replaced, but with this ability to turn, most of the "cannon fodder" will be coming from a background that hasn't actually taught them to view themselves as cannon fodder.
For vampire clans where this bigotry is overt, on-the-books marginalization of the non-cambions, where failure to do what the cambions say is punishable by death (and the incentive to become a vampire in spite of all this is the general license to abuse your power that these more villainous clans grant), this doesn't matter as much. But if I want to explore this bigotry in a less overt fashion, more in the form of cultural values and social enforcement, I'm having trouble imagining how this sort of culture could survive when it keeps getting new members who are naturally inclined to see it as nonsense, and nonsense that comes directly at their expense.
How can I stop the regular influx of people who weren't raised as vampires from inherently undermining the culture of "species patriotism" among the lower class that these immortal clans rely on to flourish?