We teach them that sex is good and powerful, uniting people emotionally, and creating new human beings in the process. Sex, sexuality, and our sexual parts are not shameful, but rather, they are personal and private. It is something to be shared with the right people; trustworthy people. Obviously this includes parents and doctors in appropriate settings, and eventually it will include a wife, or a husband.
We have given them a full understanding of intercourse and the reproductive cycle. But we have not talked with them about specific sexual acts other than intercourse, except as those questions arose from our children's conversations with other children. This is because those are things that are properly explored within the context of a wife and husband who are bound together for life.
We have taught them that all good things can be abused, including sexuality. We have taught them that our personal desires are often the enemy of our own health, and that this is true in the realm of sexuality as well. Sexual irresponsibility is destructive to the individual, and to those they are in relationship with. It is emotionally destructive to self and others, and it can be physically destructive to self and others.
We have explained to them that our culture enshrines the pursuit of personal desire as the highest ideal, and that this leads to much confusion and experimentation in many areas of life, particularly sexuality. Most of their peers will be having sex before marriage, and many of them will be experimenting with their sexual behaviors, their sexual identity, and even their gender in ways that will cause unnecessary pain.
We have taught them to be respectful of the choices, behaviors, struggles, and identities of other people, and that all people are to be treated with reverence simply because they are people. But we have also taught them that many of those choices, behaviors, struggles, and identities aren't healthy, and that they should avoid those behaviors personally.
We have talked with them briefly about sexual addiction and pornography. We have also explained more exhaustively how sex outside of marriage builds intimacy with someone other than your spouse, and that this will cause pain and confusion later on in life. Extra-marital sex can also lead to unwanted pregnancy, disease, and even death.
We have taught them explicitly to wait until they are married to engage in sexual behavior, but we have also interacted with them quite a bit about the messages they receive from peers and cultural figures that contradict that wisdom. We have shared with them some of our own personal history with sexual behavior (both our mistakes and our successes).
We have also talked with them about grace and forgiveness, and how one mistake, or even a long pattern of mistakes, can be forgiven and overcome, no matter the consequences.