A recent study published in the International Journal of Andrology has claimed that would-be mothers who have high levels of phthalates in their bodies are more likely to give birth to boys who exhibit less masculine behavior. The study says that these boys are "less willing to join rough and tumble games" and less likely to play with "male toys".

Phthalates is a chemical used to soften plastic and found in everyday common products. Although the manufacturers have time and again stressed that it is safe, the EU has banned its use in cosmetics, teething rings and children's toys. It has been discovered that phthalates tends to mimic estrogen, the female sex hormone.

For the sake of research, urine samples from mothers in the 28th week of pregnancy were taken and tested for levels of phthalates. The women gave birth to 74 boys and 71 girls and were contacted at the time when their children were aged between 4 and 7 to enquire about their behavior, characteristics and toys of preference. Boys of mothers whose samples had high levels of 2 types of phthalates – DEHP and DBP –preferred "feminine play", but the levels had no effect on the girl child.

In the wake of the findings, authorities are looking for ways to try and do away with the use of phthalates all together because no matter how hard pregnant women try, they will still be exposed to it all the time thanks to its use in plastic furniture, shoes, PVC flooring and other everyday items.