A woman’s brain is not fully developed until 25yrs?.
I’m not sure where that assertion began, in my experience most 18yr olds are pretty mature, they dont always make the sensible decision, what to them is a rational decision. That however can be said of any age or sex, silly or emotional decisions are not uncommon.
Most 16 yr olds can make decisions for themselves, when they are sober, it’s when they are intoxicated that things go wrong. Also we allow our children to become sexualised too early, before they are able to make rational decisions, this can affect them for the rest of their lives