What is known about the hormonal and neurological foundations underlying the differences between male and female behaviour? How are our cognitive skills affected? The originality of this book lies in the demonstration, supported by scientific evidence, that sexual hormones act on the organisation of the brain from the very early stages of life, with the result that factors such as environment, background and culture act on very different brain structures, depending on whether it belongs to a man or a woman. It could therefore be said that there are female and male brains or, at least, gender-based ways of thinking and acting. The latest biological and cognitive research presented here casts a new light on a highly controversial social issue.