Geoffrey Landgraab did just that at the hospital right after my sim gave birth. He just walked into the room, took her baby, and disappeared. You may say Eliza Pancakes is the worst, but I disagree. Geoffrey and Malcolm are anathema to any of my sims, and I do not shed a tear when something bad happens to them. I even have a wallpaper of a screenshot of Geoffrey dying of old age.
When my sim did get back home, her baby was in their bassinet, sleeping soundly. But who knows what Geoffrey might have done....
(I don't consider it a bug. Much as it is creepy and such, I feel it is very dramatic and adds to the game.)
