As the fourth over a span of about 40 years, this study further characterizes the human sex ratio of families of students enrolled at Western Kentucky University, Bowling Green, KY. Student respondents provided data on the parental, present, and projected generations. Survey results permitted calculations of average family sizes and sex ratios that were used in comparisons with results of the previous studies. Average numbers of children were 4.04, 2.58, and 2.45, and secondary sex ratios (males∶100 females) were 102, 108, and 141; respectively, for the parental, present, and projected generations. Average family size decreased progressively during the period of study. Secondary sex ratios ranged from 97 to 108 males∶100 females. Gender composition of the first two and three children influenced parities in two ways, namely preference for both genders and preference for males. Results of the present and previous studies indicated that the most desired families consisted of two children, both genders, and the male born first. Realization of this preference would contribute toward a balanced sex ratio. Other preferences included more male than female children. Overall, sex ratios for desired families in the four studies ranged from 133 to 141 males∶100 females.