While most studies of parental sex discrimination explore the devastating social and demographic effects of a cultural preference for boys, a new studyexamines its psychological effects on the girls themselves.

Poh-Chua Siah, from the Universiti Tunku Abdul Rahman in Malaysia, asked over 800 Chinese Malaysian children questions about their happiness, self-esteem and, most importantly, if they felt they were treated differently by their parents because of their sex.

The Chinese community in Malaysia was a good choice for such a study. Although Malaysian culture in general does not prefer one sex over the other, a preference for boys is clear among Chinese Malaysians, to the extent that sex ratio at birth in that community is now imbalanced.

Dr Siah found that perceived parental sex discrimination (PPSD), happiness and self-esteem were negatively and significantly related, but, crucially, just for girls. Simply put, daughters who felt their parents preferred sons were less happy and had lower self-esteem. Conversely, parents' perceived sex preferences had no effect on boys' reported happiness or self-esteem.

With a strong preference for boys a feature of many global cultures, Dr Siah's results, outlined in the The Journal of Vulnerable Children and Youth Studies, have wide implications.

"Based on previous studies that revealed negative psychological impact associated with low self-esteem and low happiness it is expected that there are more negative psychological impacts of PPSD on daughters and [it] needs to be explored further," Dr Siah concludes.

"This report suggests that parental preference for sons did have significant psychological impact on daughters, so more effort should be invested to analyse the consequences of the cultural preference for sons."

Future studies of the effects of PPSD should take interviews, observations and input from parents, as well as reports from the children themselves, into account. With many of the world's females living in cultures, where a preference for sons is expressed, it is crucial to understand the potential damage such preferences can do.