Actually, behaviours can be genetically programmed in much the same way that physical traits are. Beavers build dams instinctively, for example, even if they've never been exposed to damn building before.
This supports the idea of morality being subjective. Different society with different rules and different values, and you'll get different morality. That's why some cultures think it's okay to chop your hand off if you are guilty of theft, but we would think that's wrong.
Again, this speaks to subjective morality. Different behaviour patterns and group dynamics would lead to different moral views.
Again, subjective.
Sex with children in the group causes harm to individuals within the group, thus causing harm to the group. Since the rapist relies on the group to survive, harming the group harms the rapist, and thus the rapist is likely to die and the meme (I use the word here in the original sense, as an idea which can spread, analogous to a gene carrying physical information) that encourages child rape will die out. However, groups with the "don't rape children" meme will avoid the harm caused by child rape, and are so more likely to survive and spread the "don't rape children" meme.
But this only applies to cases where the act is going to cause some amount of harm to the person who carries it out. If the act is NOT going to harm the individual carrying it out, then there's nothing stopping it from spreading. For example, sea otters are known to rape baby seals, and even pet dogs.
SOURCE. However, since such actions do not directly harm the otters, there is nothing driving such behaviour to become rarer. Similarly, a lioness will mate with a male lion after he has killed her cubs. I couldn't image going to bed with someone who had killed my child, but in a lion pride, that kind of action would only cause harm, since it would mean that there were no offspring at all, and the pride would die out (taking with it the "don't reproduce with the ones who killed your cubs" meme).
And emotions are subjective, not objective.
Not sure what you're saying here. Sex is fun, and people like sex. Generally speaking, at least. You don't need sex for love, and you don't need love for sex.