I'll admit to being pretty clueless about gay rights issues in my younger days. I was shockingly old before I knew my first out gay person (Out to me, at least. There were people I knew who were gay but they weren't out to me. That distinction matters, as while it wasn't their job to educate me, not having conversations about this stuff, not having gay people just being a "normal" part of life, made it easier for me to be clueless.)
But even clueless me knew DOMA was bullshit, and less clueless me knows that justifications, 19 years later, for DOMA are even more bullshit.