Whether you're a kid or not depends on whether you have a stable income and take responsibility for yourself and others. I know 40-year-old kids and 17-year-old men.
Edit: Since I've been called out as sexist, I should note that I apply this equally to women. I've likewise met 40-year-old girls and 17-year-old women, and the difference between them is the same: The capability to earn a stable income and take responsibility for themselves and others.
Sometimes being part of a partnership means you focus on internal rather than external roles: Supporting the family instead of earning an income. Who does what is then negotiable within the family, and that's OK.
Edit: Since I've been called out as sexist, I should note that I apply this equally to women. I've likewise met 40-year-old girls and 17-year-old women, and the difference between them is the same: The capability to earn a stable income and take responsibility for themselves and others.
Sometimes being part of a partnership means you focus on internal rather than external roles: Supporting the family instead of earning an income. Who does what is then negotiable within the family, and that's OK.