Monotheistic religions tend to have a theodicy problem, essentially, where did evil come from exactly? And how does that all work? Apologists have been gnawing on this bone for centuries. Evolution has an evil problem, too. It's called eugenics. What's the mechanism for evolution? Adaptation. Living things change slowly over generations in an effort to adapt to the environment. Or one generation. There was the London Moth at the height of the Industrial Revolution. It was normally white, because white blended well with the surroundings and white moths avoided being eaten (and there fore able to reproduce) at a much, much higher rate than black moths. Until the I.R. came along and spewed coal all over everything, rendering the background black. So, the black moths suddenly blended and the white ones were easy prey. The shift in black moth vice white moth population in a year or two was dramatic. There were few white moths and many, many black ones. It all came down to the fact that the local birds ate the moths they could see. The moth population adapted to that fact.
Now, human beings have taken themselves out of the evolutionary chain. Humans do not adapt to the environment. Humans adapt the environment to suit them. That means that we have not only become the most populous species on the planet, we're also at something of an evolutionary standstill. The folks that wouldn't have had a shot at reproducing and sending their icky genes on down the line no longer have those problems. We use technology to not only allow them to have a long life, but to pass their genes on. So, practically anyone with a genetic malfeasance is passing that on. This is where eugenics rears its head. The theory itself is not evil. It merely espouses the idea that only people with good genes should reproduce and everyone who has genetic problems should not pass those genes on. So, people who have things like lupus, epilepsy, or a really low intelligence, wouldn't have babies to pass those ick genes on. Now, where the evil of eugenics pops up is who gets to decide where that genetic goodness line is? Who gets to draw the line about what genes are good to pass on and which genes are not? I have epilepsy, but no one in my familly for a few generations back has it. Should I be barred from spawning? On the converse, I have a really high IQ, which many people in my family for generations back have, as well. So should I be required to spawn?
Luckily enough, we've got a global political climate that says spawn away, people. No one is gonna tell you not to have children. Except China, but they're not telling certain people they can't have kids, they're telling everyone how many kids they're allowed. Population control (another sticky subject).
But, as a person who subscribes to evolutionary theory, this is an ethical sticky point. On one hand, it's unethical to decide who has privilege and who doesn't based upon things they cannot control. On the other hand, it's unethical to pass on genetic disorders and diseases to the next generation. Perhaps the "designer baby" technology will fix these problem, though I imagine the whole host of ethical problems associated with it will make this technology just as unattractive, ethically, as eugenics.