A team at the University of Rochester studying the safety of phthalates -- chemicals in the plastic used in many household objects – found that they can actually disrupt hormones, according to BBC News. The chemicals affect the baby's developing brain by deactivating testosterone, the male sex hormone, according to the BBC.
The boys exposed to high levels of two phthalates were less likely than other boys to play with guns, trains and cars, says the BBC, and they seemed less likely to join in "rough and tumble" games, according to the Daily Mail.
While some experts think phthalates may be partly responsible for lower sperm counts in men over several decades, this is the first study to link kids' behavior to hormone-mimicking chemicals, according to the Daily Mail.