1. The immature parents have so many infantile traits themselves.
    这对儿未成熟的父母本身就有不少孩子气。

2. The immature parents have so many infantile traits themselves.
    这对儿未成熟的父母本身就有不少孩子气。

3. Don´t use such baby talk! People will think you are mentally immature.
    别说这么孩子气的话！别人会以为你心智未成熟。