Elven Maturity Rates: Backstory Advice

At what rates do Elves mature into adults? I know it says that they reach adult hood at age 40, so do they go through childhood and adolescences over the course of 40 years, or is the 40 year things more about education/life experience, with them maturing at the same physical rate as humans?

The reason I ask is that one of my player characters, a Wood Elf Rogue, raised his sister's children as his own after a terrible war killed off most of his family, his sister included, as well as most of his people.

The war was thirty years ago.