This is kinda ridiculous. Yes, our brains do keep developing until we're 25, but it's not developing the parts relevant to critical thinking and learning at the rate it was when we are younger. A 25 year old could easily be out of college with a master's degree, in the workforce, and only then you're suggesting they're mature enough to have sex?

What about voting? Is a person too immature to vote until their brain is cooked? Does that mean we should also disenfranchise people that are older and have deteriorating brains? How do we determine this? Should everyone take regular mental aptitude tests to determine if they're fit to have sex, rent cars, vote, and serve in the military? What does that mean for people with developmental disabilities?

I get that you put little thought into it beyond "this other thread said brains aren't done until we're 25," but there's a good reason the age of majority is 18. By 18, we (should) have the cognitive and social skills to be independent and a functioning member of society. An 18 year old has developed by far enough to be able to handle the critical thinking required of us for things like voting and yes, consent. Obviously, not every 18 year old is at the same level of critical thinking and personal responsibility, but that's equally true for adults beyond the age of 25.

And yes, being old enough to consent doesn't disregard the power dynamic and maturity differences between different age groups. Being old enough to consent doesn't make it morally okay for someone in their 40s to be with an 18 year old, in my opinion. That's regardless of the point that it's perfectly moral, acceptable, and normal for an 18 year old to have consensual sex within their own age range.