Not to sound cold, but children do not have and cannot be granted any such "right to two parents, one of each gender." That is legally and socially untenable and unobtainable. States cannot realistically guarantee any such right and would invite a veritable flood of lawsuits to suddenly declare one.
Rights are not granted by government, but to the best of the government's ability, they are protected. Based on "The Best Interest of the Child" standard, written by the state's supreme court, it's an already an implied right in Wisconsin.
There are many good things that are not guaranteed rights. Does that mean the state should embrace social policy that works directly against theose things? No way.