It depends on the intent - 'juvenile' can have negative connotations. If it's not intended to be a humorous but negative contrast, you might go for an antonym to 'adult' instead of 'parental,' like child, youth, or kid.
JBS Haldane's Four Stages of Scientific Theories:
1. This is worthless nonsense.
2. This is an interesting, but perverse, point of view.
3. This is true, but quite unimportant.
4. I always said so.