WWE Paige started wrestling in her early teens here in the UK, but that was for her parents company and in a controlled environment and she had grown up surrounded by the business. I'm sure there are other 2nd & 3rd generation wrestling children who's parents have encouraged them to take it up at an early age but it comes down to the environment that they are learning and competing in. I wouldn't condone anyone putting on matches between children unless they were properly supervised and trained and equally the idea of a young child taking on a full grown adult is abhorrent regardless of the situation