I can't form an opinion from a legal perspective however what I can say is that we are much easier to be influenced by others when we are in our early 20s. Call it lack of experience or lack of full brain development, but back to the point of my story, a young person maybe stirred by a more mature person (in both good and bad ways) because they are yet so "moldable". Speaking from my experience, I can say that my boyfriend who was seven years older has shaped my personality and without his presence, I would have perhaps grew into someone different. Furthermore, besides him I felt I left out parts of myself that defined me, such as playfulness, for instance, because he was so grown up. Well into my adulthood I realize how inauthentic I was for years, simply because I grew up next to a person older than me, and automatically whatever he said or did was more important than anything I said or did because I was younger. I understand there are more layers in what I am describing than mearly the brain development component, but looking at myself as an adult, I would have never gotten myself into such a relationship if I would have had the brain to see it through.