Would straight people?
YES. The only legitimate government interest in this area is the welfare of children, who are almost always better off in a stable home with two biological parents. That is why there are tax deductions for dependents and joint tax returns when one parent is caring for them. It was originally made deliberately difficult to dissolve this arrangement, but no-fault divorce has greatly undermined this contractual relationship.
Easily dissolvable Civil Unions should be available to all couples who want to combine their resources and legal rights, but the aforementioned tax advantages should only be available to legally Married couples with children.
So no tax deductions for children- for when a single mom is raising her kids?
As if it wasn't hard enough to be a single parent raising kids- taking away the tax deductions that married couples get for their kids is just cold.