Is it permissible for a mother to look at her daughter's thigh and what is below her navel?

It is permissible for a mother to look at her son's thigh and what is below the navel if he is less than thirteen years old. However, if he reaches thirteen years of age or older, it becomes forbidden for her to do so because he is then considered to have reached puberty. This fatwa is based on the Maliki school of thought.