Oh look! All these famous evolution scientists, and members of the Darwin family, just happen to have been collectivist exterminators... Darwinism-Eugenics. Merely a coincidence, you say.
The religion of evolution holds forth no hope of a perfect millenium in which all evil shall be eliminated and all struggle shall cease... There can be no progress of any kind without struggle... The struggle against evil in general is thus a condition of social progress... Evolution thus offers a rational solution of the great problem of evil. It has taught us that there is all about us a great and world-wide struggle for existence; that inaction and satiety end in degeneration and that advance can be purchased only by struggle, suffering, and death.--E.G. Conklin (AAAS president, American Eugenics Society president), The Direction of Human Evolution, pg. 239--240.
Once the full implications of evolutionary biology are grasped, eugenics will inevitably become part of the religion of the future, or whatever complex of sentiments may in the future take the place of organized religion. It is not merely a sane outlet for human altruism, but is of all outlets for for altruism that which is most comprehensive and of longest range.
--Julian Huxley (co-founder of the Modern Synthesis of evolution), Man in The Modern World second edition, 1950, essay Eugenics and Society.
No, I don't say it's merely a coincidence. What I say is that evolutionary theory is an observation of a principle being enacted all around us, whether we want to acknowledge it or not. It's just there, and it couldn't be simpler: those that survive, reproduce, those that die, don't, and with every birth genetic changes occur. Therefore the changes that survive, do so because they help survival, because they did not die before reproduction.
Eugenics, however, is the concept of taking this observation and using it to justify mass murder. It doesn't matter if Darwin himself (let alone scientists or his family) want to do this (and Darwin didn't), it's still eugenics and not evolutionary theory.
As I pointed out, fire fighters study the process of fires. They understand in incredible detail how and why fires act. That knowledge does not make them arsonists, even if arsonists study the exact same information to commit arson.
Critical thinking - get some today.