The vast majority of countries set their ages in the range of 14 to 16; only five countries, Cyprus (17), Ireland (17), Malta (18), Turkey (18) and Vatican City (18), do not fit into this pattern.
The laws can also stipulate the specific activities that are permitted or differentially specify the age at which a given sex can participate.
In countries such as India, China and Nepal sons have been favored over daughters.
In many jurisdictions where prostitution is legal, it is regulated, in others it is unregulated.
The factors are: (1) A preference for sons which stems from household structures “in which girls and women have a marginal social, economic and symbolic position, and consequently enjoy fewer rights.” These household structures also focus on security in which sons are expected to provide support to their parents throughout their life; (2) Technological growth of prenatal diagnosis which allows parents to know the sex of their unborn child; and (3) Low fertility which increases the need for sex selection by reducing the probability of having a daughter in smaller families.
The United Nations Population Fund states that “Local fertility restrictions and spontaneous rapid fertility decline below replacement levels tend to compel parents who want both a son and a small family size to resort to sex selection.” In many cultures, male offspring are desired in order to inherit property, carry on the family name and to provide support for parents in old age.
It has been marketed under the title family balancing.
According to the United Nations Population Fund, the reasons behind sex selection are due to three factors and provide an understanding for sex ratio imbalances as well as to project future trends.