In one study, scientists analyzed population data from 1964 to 2007 in the United States and 39 European countries  They found that between 1964 and 1975, the birth rate of boys was higher than that of girls in all countries  A similar phenomenon occurred in many Eastern European countries after 1986  Scientists have analyzed that this phenomenon is closely related to nuclear power plant leakage and nuclear testing caused by radiation leakage
Experimental results show that nuclear radiation particles have some damage to the x chromosome in sperm. After exposure to radiation, male offspring have a higher birth rate than females
 The former appears mainly related to atomic experiments in the 1960s and 1970s, while the latter is likely to be linked to the Chernobyl nuclear accident