Childhood is the age span ranging from birth to puberty, which begins at around age eight. Biologically, girls and boys are quite similar at this age since ovaries and testicles don't produce sex-specific hormones yet. [1] [2]

However, they soon discover differences among themselves, for instance, that down below they look differently. In games with each other and peers children start to explore their body.

At the beginning of the 20th century, Sigmund Freud proposed that all human beings, from birth, possess a sexual energy that develops in stages - the anal, oral and genital. [3]
More modern approaches deal with the development of sexual competencies which starts in childhood and is a life-long process. [4] The first observation of an orgasm was recorded by the sexologist, Dr. Kinsey when a surprised mother watched her three-year-old daughter. [5]

Apart from sexual development, children also undergo a social influence. Infants are often dressed in blue or pink shortly after being born. And even before that, the first question mostly refers to the baby's sex. This focus turns out to be particularly complicated when there is no clear assignment. [INTERSEXUAL]

It's still unclear, if girls' interest in dolls and boys' interest in technology is inherent or acquired. In this respect, scientific research has schown interesting similarities of primates and humans. Boys as well as male chimpanzees are mostly interested in technology, for instance toy trucks. Girls as well as female chimpanzees seem more versatile. They equally play with plush toys, like dolls and stuffed animals, but also with technical toys. [6] [7]

Apparantly, there are inherent differences between boys and girls but the socialisation and influence start in childhood. In total, men and women are regarded as very different groups. According to current adult research, other factors like educational background, income, health and attitude to life reveal a lot more about a person than his/her sex. [8]