Oestrogen, not testosterone, is what makes a male act like a male
IN ALL species that practise sexual reproduction, males and females show gender-specific behaviours. These range from the way they mate to the way they defend—or fail to defend—their territory. Both males and females start out with the same template at birth, but then something acts on the male to masculinise him for life. But nobody knows just how that happens.
It is well known that sex hormones like oestrogen, which is typically seen as a female hormone, and testosterone, similarly seen as a male one, play a role in shaping the neural circuits in the developing brain, and that much of that moulding takes place before birth. It has also been established that testosterone, as well as being a fully functional hormone in its own right, can be (and often is) converted into oestrogen in the body. ..