The brains of most humans, as well as most animals, develop specific brain characteristics during gestation. For examples, portions of human male and female brains are of a different size and may have differing numbers of neurons. During prenatal development, the brains of most animals, including humans, develop specifically male or female characteristics. However, researchers knew little about how this differentiation occurs. In most cases, the type of brain (male or female) matches the body in which it is housed. Sometimes a person’s brain doesn’t match the body in which it was housed. Again, how and when this occurred during the process of gestation has not been clearly understood. Enter a new study by researchers at the University of Maryland School of Medicine. Part 2 tomorrow.