Paying more to people with more dependents effectively discriminates against several classes which are protected in the US:<p>- Those who for medical reasons cannot have children.<p>- Those who for (lack of) religious reasons do not have lots of children (families with 6+ children have a different distribution of religious beliefs than the overall population).<p>- Homosexuals.<p>On the other hand, paying less to people with dependents (why?) effectively discriminates against:<p>- Heterosexuals.<p>- People who for religious reasons have lots of children.<p>- Disabled dependents (not a protected class in the US, but maybe it should be!).