If Citizens United is to stand under auspices of Equality Under Law:
Any entity which does not waive rights to it's every creation after 18 years of maturation may not claim personhood.
People loose the tax and labor benefits of having children after 18 years. Should corporations wish to retain 'personhood' they would have to give up their children/creations after 18 years, i.e. Patents, copyrights etc. To maintain Equality under Law. A corporation which may benefit from it's past creations with no actual current production value of it's own is tantamount to slavery. Unless the government is willing to extend to parents throughout the country to NOT certify their children as adults when they turn 18 years old, equality in law cannot exist as corporations have an unquantifiable advantage.