My Alien daddies.
Grown-ups, full adults, once they make it back to mother planet, they regress back to baby ages, their body would shrink, they still might look like teenagers or pre-teen, but their mind would be same as a baby.
Compared to our caregivers, we are the size of little toddlers, like it or not, you are treated like a baby literally, but only in short thirty years, you'd be an adult. Yes, humans would grow up, they'll be adults like the aliens we belong to now, we need care, love, discipline until we make it.