There is no way in anybody's healthy perspective that 39 is a kid. If you're a woman you're looking at your fertility being almost over at that age and yet to someone who is a few decades older you're a kid? All you are is not old.
I think it's nuts to think 29 year olds are kids.
If little Rod Roddenberry was 19 and making a youtube about how he had just discovered his Dad made OMG Star Trek I would laugh at his kid-ness but that's about it.