What is the reasoning for the age limit on adoption being 20 years old or younger?

Answer

The Adoption Act 1955 allows for a child to be adopted and defines a child as a person who is under the age of 20 years. This definition was amended by the Age of Majority Act 1970, which reduced the age a person is considered an adult for all legal purposes in New Zealand from 21 to 20 years old, unless otherwise specified by the relevant legislation.