Every time someone drops the "generational breakdown of ethics" idea, I can't help but think that we really can't have fallen that much ethically when we used to have legal slavery, legal disenfranchisment of the poor, and so forth. On the other hand, in a lot of ways we have found more subtle and palatable ways for groups to seek power over others.
In the end, I just think that over time, the "goodness" of human ethics has been more or less stationary. We've got wants and needs. We've got empathy. We've got conscious minds that seek rationalizable patterns of behavior that satisfy both of these things, but the end result isn't really a consistent normative ethical scheme. Even the most religious people (obviously) find ways to bend the spirit of the ethical schemes to their own benefit.