Changes

It seems odd that a person could change so much, that it makes them unrecognizable.

It's quite common. I've seen it in both boys and girls.

It is also observable in species such as gorillas. The young are very friendly and cooperative, and love to learn things - the adults become set in their ways, often unfriendly, and competitive.

In some neotenous animals, such as humans and dogs, the juvenile stage is stretched out, some degree of plasticity of mind is retained into maturity, and many traits of childhood are retained. Even so, most adults lose the ability to easily learn a new language and some other abilities. Of course, the degree to which this happens differs by person. I tend to think that peds are just a bit more neotenous than average.