At some point, the impact of the environmental improvements will peter out and intelligence will begin to decline. The best available estimate of the rate of this decline is that it will be about one IQ point per generation. The third respect in which modern populations are deteriorating is moral character. This broad trait comprises self discipline, the motivation to work for long term goals, law abidingness and a sense of civic responsibility. It is conspicuously lacking in criminals and in the underclass with its sociopathic value system.
Moral character has a genetic basis.
This has been established by twin studies, which have shown that identical twins separated shortly after birth and reared in different families are quite similar in respect of their moral character, showing that a genetic determination is involved. In addition, it has been found that adopted children resemble their biological parents more closely than their adoptive parents, showing that moral character is transmitted genetically from parents to children. From the last decades of the nineteenth century those with weak moral character have had more children than those in whom moral character is strong. There are various ways in which this has been shown. For instance, male criminals have about 70 per cent more children than the law abiding population, while among females in the United States in the first half of the 1990s high school dropouts had an average of 2.6 children as compared with only 1.8 for American women as a whole.