Do you like [all] children?

I often hear people claim they like children. This usually means all children, though not necessarily everything a child does.

The reverse is also true: People who do not like children rarely make exceptions for individual kids.

This always strikes me as odd. What characteristics do all young humans share? Do you think there is a quality of “childlikeness” which is what we are talking about when we say we (dis)like children? Enthusiasm, maybe? Level of activity?