According to Dr Satoshi Kanazawa who led the research at the London School of Economics said that attractive parents are 26% more likely to have a daughter than a son as their first child.
This is because physical attractiveness is heritable and because daughters benefit from attractiveness more than sons. He said that this is bases on which each sex have survived for long years. Men's reproductive success depends largely on status and women's on the youth and physical attractiveness. The research was published in the Journal of Theoretical Biology. The research analysed more than 20,000 American. Only first-born children were included in the analysis. Beauty was rated depending on their height, weight, apparent age and all factors that can be used to judge basic attraction levels without subjective viewpoints.