Gray E, Duckworth D, Nakajima Y
J Hered. 1980 Nov-Dec;71(6):411-5. doi: 10.1093/oxfordjournals.jhered.a109397.
In 1979 sex data were obtained from 861 Japanese students from three upper secondary school (Katsushikano, Ogikubo, and Kiyose) located in the residential, metropolitan area of Japan. Average numbers of children per family were 5.16 for the parental and 2.43 for the present generation. Secondary sex ratios were 106.9 and 104.9 for the parental and present generation, respectively. Neither the similarity or dissimilarity of sexes nor the proportion of males in existing children was significantly associated with family size in the present generation. A significant positive correlation was found between sexes of child 1 and 2 in families of two or more children. None of the other correlations between successive births or between nonsuccessive births was significant. Observed frequencies of combinations of sexes within families of the parental and present generations did not differ from expected frequencies. The family most preferred by both male and female respondents consisted of two children representing both sexes with the first-born being male. The desired families were characterized by an average of 2.35 children and a resulting sex ratio of 122 males: 100 females.
1979年，从日本大都市居民区的三所高中（胜岛野、荻洼和清濑）的861名日本学生那里获取了性别数据。父母那一代家庭中每个家庭的子女平均数为5.16个，而当代家庭为2.43个。父母那一代和当代的第二性别比分别为106.9和104.9。当代家庭中子女的性别异同或现有子女中男性的比例均与家庭规模无显著关联。在有两个或更多子女的家庭中，第一个孩子和第二个孩子的性别之间存在显著的正相关。连续出生的孩子之间或非连续出生的孩子之间的其他相关性均不显著。父母那一代和当代家庭中性别组合的观察频率与预期频率没有差异。男性和女性受访者最喜欢的家庭由两个孩子组成，两个孩子性别不同，且第一个孩子为男性。理想家庭的特征是平均有2.35个孩子，由此产生的性别比为122名男性比100名女性。
