Sexual exploration and play is a natural part of childhood sexual development, and helps children to develop physically and emotionally. Throughout their development, every child will express themselves sexually in different ways.
A child’s behaviour will depend on their age and circumstances. The NSPCC website describes the behaviours typical of each developmental stage. It is normal to see a child exhibiting behaviour that is slightly more or less mature for their age.
Taken from www.nhs.uk
The NSPCC have recently published a Harmful Sexual Behaviour Framework: An evidence-informed operational framework for children and young people displaying harmful sexual behaviours (PDF) which uses the following definition:
“Sexual behaviours expressed by children and young people under the age of 18 years old that are developmentally inappropriate, may be harmful towards self or others, or be abusive towards another child, young person or adult.”