A general point

In general (and paradoxically), large minorities (as women, US blacks, and children) are easier to culturally dominate than small ones (as gays or Jews); because many members will have something invested into the status quo, and others will be lucky enough to have a good position despite their status. A small minority is much more self-conscious and "paranoid" about its rights being violated.

This is one great reason that Slave Emancipation and Women Suffrage were never as popular with their own base as repeal of sodomy laws was with its. And it very much applies to children too.