People like that should be sterilized and never allowed to have kids again.
Starving your own kid to death is the work of a monster.
20 years is too light for what they did.
Meh, I’m old school. I say “let the punishment fit the crime”. Give them one “hot dog smoothie” a day, make them sleep in a closet they cannot lay down in for no more than 4 hours a day, and force them to do hard labor til they drop.
Oh well, I guess that would be “cruel and unusual” punishment. Just hang ‘em then.