Parental teachings are always given with the best of intentions and are put forth with the intent of providing a set of guidelines for children to follow in order to grow up with the same ideals as their parents. When dealing with sexual interactions the parental teachings of those adhering to the Christian faith tend to be rather limiting and rigid.
Christianity has always maintained that it is the only true spiritual path to follow and all other ways are at the very least misguided. As a patriarchal religion the men of this religion have come up with ways and means of ensuring that the line of succession follows the male as opposed to the female of a couple. Parental teachings meant to ensure such a succession make much of abstinence and not giving in to physical attraction and risk.
As a general rule no matter the religious, political or other agenda parental teachings are meant to provide a basis for mature behavior and to keep the child and/or children safe from harm. This is no better exemplified than through Christian doctrine. Give in to physical attraction and risk the wrath of God not to mention that of the neighbors. Those who don't follow parental teachings and have sexual relations not condoned by the Church have through the centuries been made fun of, ostracized and killed.
Not following parental teachings when it comes to the matter of sexual relations can result in the spread of disease. When one has more than one regular partner it's much more likely that one will contract a sexually transmitted disease at one point or another and of course transmit that disease to others. Christian parental teachings promote the conception of monogamy.
Christian doctrine grew out of the teachings of Jesus Christ as put down on paper by his disciples and revolves in general around ways and means of making life more equitable and fair for all involved. Some of those who have interpreted the words since their initial writings have taken the concepts and exaggerated them to serve their own personal agendas. An unfortunate occurrence that has occasionally resulted in issues of frustration and violence.
Physical attraction and risk is something that Christian parental teachings talk a lot about. Christianity separates the body and its sexual desires from the spirituality of every living being. In order to maintain control over humankind's sexual interactions Christian doctrine places sexuality in its own little box and attaches a multitudinous amount of stigmas and constraints geared towards keeping its subjects in line.
There has been a shift of late in some of the teachings towards a more open minded and frankly realistic view of humankind's sexuality. It's becoming more and more popular to equate sexuality with being a bodily function that shouldn't be hidden and repressed but rather explored and enjoyed. It promotes both physical and emotional health. Just by virtue of enjoying the physical act of having sexual interactions one isn't denouncing ones allegiance to God but rather exemplifying it.
This new shift in Christian beliefs hasn't, by any stretch of the imagination, infiltrated all the denominations and variations of the Christian faith. It is, however, being bandied about with more and more regularity and there is a plethora of adherents to a more relaxed standard. These people are including this relaxed version in their parental teachings endowing their children with an ethical standard that is both reasonable and healthy.