During the first eight weeks of development in the womb, all our brains were female. Following that phase, however, a tremendous surge of testosterone remaps everything, from neurons to reproductive organs. As a result, almost half of those embryos undergo a change. Aside from testosterone, another hormone, estrogen, has a substantial impact on another area of the human body. It will also aid in the development of a woman's physique and brain.

From birth until her first birthday, a typical female infant's brain is flooded with estrogen levels that can reach adult woman levels. Her brain's communication centers react to this hormone by generating additional neurons, preparing her to communicate with others. This region of her brain also makes her very attentive and open to facial emotions, particularly those of her caregivers. Female newborns often spend their first months infatuated with faces. Whether she can talk or not, the female infant will demand and expect the listener's undivided attention when she begins to speak. Furthermore, female brains are more sensitive to the emotions expressed in the voices around them. Females experience a considerably different first year than their male counterparts. High testosterone levels of boys at this age have made them less chatty and more concerned with activity and exploration.

But just after they reach the 1-year age, the newborns' testosterone and estrogen levels start to decline drastically. In the following ten years or so, we will see the remarkable similarity between their bodies. Yet, their minds will continue to be separate, which causes some behavioral differences. The brain structures that elevate estrogen in a female will keep her conversing and watching throughout her play. She'll probably engage in continuous dialogue with everyone and everything around her, including her toys, parents, and friends, and her emotional memory will remember every detail.

While she may believe that her time as a girl would never end, this phase of low, steady hormones is only temporary. Her world could seem to be collapsing around her as her hormones fluctuate. However, it’s only how it seems. In reality, it is just a period of puberty.