season 8, episode 4, "King County," returns to Georgia, and its story reaffirms a disturbing fact in universe: those who succumb to the virus don't age. This means that any children unfortunate enough to be bitten will remain at their current age until all of their flesh finally rots away, as exemplified on-screen by Morgan Jones' son, Duane, who was last seen in season 1 of the main series.
In 's very first episode, "Days Gone By," Rick meets Morgan, his young son Duane, and his wife Jenny - or at least what remains of her. Jenny, now a zombie, is roaming the streets as Morgan couldn't bring himself to take her out completely. After Rick departs Morgan and Duane's hideout, the pair aren't seen again. Morgan returns in season 3, dazed, confused, and without Duane - leaving the child's fate hanging in the balance. Now, however, has revealed what happened to Duane.
As Morgan couldn't bring himself to put Jenny down, she eventually bit Duane, causing their son to also turn into a walker. As events unfold, it's revealed that not only did Duane suffer at the hands of his own zombified mother, but once again, Morgan couldn't bring himself to deliver the final blow to a loved one. Instead, he chose to chain Duane to a bed in the attic, where he's remained stuck for 10 years; a decaying, distressed, 10-year-old zombie.
While the revelation about Duane's fate draws one long-standing mystery to a close, it also opens up another. While the world of obviously runs rampant with zombified adults, children are few and far between in the universe. In "Days Gone By," Rick does encounter another child-age walker, an unnamed little girl. There are other important examples of young children suffering the awful fate, like Sophia in season 2 and Penny Blake, the governor's daughter, in season 3. Compared to adult zombies, however, there are startling few throughout the course of and its spinoffs.
There may be a good explanation for the lack of young zombies in universe, however. The infected only live for as long as their flesh will allow. Though they don't technically age because of rigor mortis, a human who has succumbed to the virus will still decay due to their flesh rotting away. This could mean that any child-age zombies simply rot faster. In addition, child zombies would likely be much less difficult to take down than their adult counterparts, making them easy targets for survivors to eliminate. Even more disturbingly, a child's smaller stature may mean they get devoured by the rest of the zombie herd early on.
On a more practical level, may avoid storylines that heavily involve zombified children due to the complication it brings to production. Thanks to child labor laws, which vary from state to state, actors under the age of 18 are restricted on the number of hours they can work. For a show like , where the child may need to spend additional time in hair and make-up as well as work long hours on set, it's likely impractical to have too many young zombies roaming around.