First, for at least most people, there are studies which show that working graveyard shift not only violates societal norms (like the three square meals a day example), but is actually bad for the person’s health (not significantly bad, but an effect is noticed) due to an absence in certain spectra of light from the sun which affects chemicals in our bodies. I can’t immediately cite a source, but I have heard it from multiple sources.
Doesn’t this show what is already evident from the way our eyes function? Namely, that human beings are ordered toward night sleep-- an order which is frustrated by taking the graveyard shift? night owls may have a desire to stay up late, but their eyes are ordered in the same way as the rest of us. Is this not similar to the disordered desire of people who suffer from same-sex attraction?
As far as consequences go, yes, graveyard shifts help society to function, which is ultimately a means to the end of greater human well-being. However, many could argue, and in fact have argued, that same sex unions also improve human well-being by allowing people who have SSA to live fulfilling lives with the ones they love.
Finally, I’m mainly looking for reasons to prevent legal same-sex civil unions. It seems that most people who believe in the separation of church and state cite natural law, so I’m trying to delve a little deeper into that basis.