It is a well established fact that people of higher IQ are having less children than those with lower IQ's. This was humorously explored in the movie Idiocrocy in which a completely average man from our time is put to sleep for hundreds of years and wakes up to find himself the smartest man in the world.
While much of the humor of this movie fell flat the question itself is a valid one. Are we as a species going to become stupid now that we have the ability to more fully control whether we have children or not?
To understand this we should first consider why it is that smarter people do not have children while those of lower IQ's do. Again returning to the movie idiocrocy we find are given a view into the likely answer. We have two couples, the first a high IQ couple, both are busy working, the woman not wanting to interrupt her career has put off having children, she later discusses how it would be difficult to have children in these current economic conditions. Other factors continue to come up until her husband dies and the choice falls out of her hands.
At the same time we watch the low IQ couple who don't think about the ramifications of their actions have more and more children and the family tree explodes as the man begins to cheat spreading his genes quickly as he has children with multiple women.
But, genetic isn't as simple as this story makes it seem. Much of what makes people intelligent is not genetic at all and while the children of the philandering low IQ man have a higher likelihood of being the same some will rebel both genetically and socially taking the place of the children that the more intelligent couple didn't have. And of course some of those smart people will have children as well. Perhaps not the twelve that the lower IQ family has, but they will seek out members of their own social group and have children as well.
The truly intelligent of our society have always been a rare commodity and this is not the first generation to face the facts that the poor both in wealth and intelligence have more children. It has in fact always been true. In the past the most common form of social welfare was being supported by your children. This, along with high mortality rates led to people having many children.
True intelligence has always been an anomaly in the human species. Those who make great discoveries are closer to genetic mistakes than genetics in action and though the ability to pass on genetic flaws due to modern medicine keeping alive those with the flaws is a trend that may lead to an unhealthier species it is likely that our understanding of genetics will soon overcome that as well. So, while dysgenics makes an entertaining humorous threat for a movie there is no real reason to worry that it will change the face of humanity.