The bad parent gerbils had another litter. The last time their babies were almost weaned before they chewed the babies’ tails and hind legs off. Outside of Florida, humans hardly ever do that.
The picture above is of one of the babies from June 12, children of Snowball and Squirrelley, who rarely eat their children. Newborn gerbils are pretty much indistinguishable so it shouldn’t be a big deal.