There are tests on the internet to help people determine if they have a male or female brain. These tests are based on the assumption that male and female brains are inherently different. But a study recently published in the Proceedings of the National Academy of Sciences concludes that brains can’t be classified in the binary categories of male or female. We speak with Daphna Joel, one of the study’s researchers and head of the psychobiology program at Tel Aviv University, about how they reached their conclusion and why it’s significant.