I don’t think the psychological development of maturity takes place like this. The physical growth of females overpowers the growth development of males, but it has no relation with an overstated stage of maturity.
Any individual’s maturity is a circumstance of events in life. It is an elixir that one cannot learn; it is not experienced and realized. Moreover, one can feel maturity; however, there is no physical place for knowing the structure of maturity.
The statement that ‘girls mature faster than boys’ is another gender biases. Maturity is not a phenomenon like puberty that would occur at a specific year of life. Often, society tells girls that they mature faster than boys, i.e., a silent sign of dictatorship. In the middle years of a girls’ childhood, one teaches her how she should act or what society expects her to do. When a man acts childishly, the situation does not bother any community. It all goes around, ‘he is a child. These are days when he can be free.’ You must have seen how cinema romanticizes such statements. The same scenario might not take place for a girl.
Contrarily, this statement is not only unfair to girls but also boys. It projects that girls must act responsibly in society while boys can wait. Like I said before, the circumstances are more in considering the path of maturity. Many of us still do not approve that psychological impact does not influence matureness in any’s life. However, only a few of us holds this statement as correct.
If you are one of those who hold this statement that girls mature faster than boys, then you are practicing sexism in your (child’s) life before s/he knows the intention behind this. Age and puberty is no deciding factor of matureness. A girl may become mature in adulthood, while a boy may become mature during adolescence. It depends on how one interprets the incidents in their life and how one chooses to react to them.