There's the Act III quest where one of the ways to go is to steal a baby. I resolved the quest without stealing the baby. A few hours later, I opened the house where the baby was and took it into my inventory. The son showed up and I had to kill him, even though the quest was already resolved.
The baby just stayed in my inventory, because there was nothing to do with it. My ending referenced me leaving Sun in Shadows with a child. Does having the baby in your inventory really put that extra tidbit in there?