The entire person, body and soul, is involved, whether you like it or not. Our culture has tried very hard to make sex casual. The body is considered to be merely an appendage or container. However, you cannot separate personhood and the body. We are what we do with our bodies.
Sex is so intense that humanity has tended to be deeply suspicious of it.
In the past 30 years, there has been a dramatic change in the attitude toward having babies in this country. The birth rate is half what it was in the 1950's. We have been below the population replacement rate since 1973. The same trend has occurred in all the developed countries. The Church recognizes that there are indeed overpopulation problems in some areas of the world, but holds that these should be handled in a non-coercive manner.