The people who perished in the flood included women and children too, but none of them survived either.....This is something I brought up to a seminary student years ago. Sodom would not have been devoid of innocents.
in all likelihood, that was because someone who consents to an activity, even if they do not commit the action themselves is also guilty in God's eyes. Children learn what they live.....so, in that environment, what were they going to learn was "normal" behavior?
If you come across a nest of poisonous spiders in your house, do you spare the babies if you already know what they will grow up to be?