Morality is not based on the continuation of the human race. You can have a moral dilemma over something entirely unrelated.
Further, the continuation of the human race, or more parochially ones own genetic lineage (or even ones own life) are motivated by survival/propagation instincts, not conscious thought that this is the moral thing to do.
Morality is not a single-issue attribute but is more related to empathic response. Our negative empathic and emotional response to an observed action is more likely to classify that action as immoral.
Strangling kittens is something you might consider immoral, because you have a strong emotional and empathic reaction to the suffering of the kitten. Some people don't have those same reactions (usually the person carrying out the action) and so don't discern any moral problem with it.
Perceived immorality isn't just a symptom of psychiatric disorder either. Slavery is considered immoral by most now but, of course, we know that wasn't always the case.
Even if you want to overlay morality onto the continuation of the human race, let's consider some of the issues that various groups cite as threats to that continuation: nuclear proliferation, global warming, genetic engineering/cloning, pandemic viral outbreak, etc..
How we tackle these issues may include moral decisions, the genetic engineering ethics one in particular. I am not persuaded that a majority moral consensus has been reached on issues like the above.
