There is a huge amount of ignorance about this subject. I agree that this is a cultural issue, not a religious one, but that's not to say that such behaviour is considered normal or acceptable, even in those cultures where it is most prevalent. Quite the contrary, honour killings are deeply frowned upon even within the cultures where they happen most often.
My DH is from a very rural community in a (non-Islamic) culture where "honour killings" are relatively common. Many of the elder members of his family are illiterate, and it is a deeply patriarchal culture in which the movements of women and girls are tightly controlled by their fathers, brothers and husbands. A couple of years ago, my unmarried niece went missing for a few months - the presumption was that she had run away with a boy. This brought great shame on the family and was a source of unimaginable angst for the girl's parents and her extended family. Eventually, she was traced and brought home. She was told in no uncertain terms that she had brought shame and dishonour to the family, but nobody laid a finger on her, and they would not have dreamt of hurting her. At the end of the day, despite their anger, they were relieved to have found her safe and sound, as she was a much loved child and part of the family. I believe that most other families in the community would have reacted in a similar fashion.
People do not kill their children because their religion/culture/society makes them do it. They kill because they are violent, abusive and controlling individuals who lack any moral compass. "Honour" becomes a convenient excuse with which they may justify their crimes to themselves, but for most people in the same communities, such actions are considered to be utterly abhorrent. We should not lose sight of this and fall into the trap of stereotyping whole communities of people as potential killers, as the vast majority no doubt love and cherish their daughters every bit as much as you and I do.