Does Mars Have Two Sexes Like We Do?

Today's world is so confusing it's hard to keep up, especially if you have a concussion, which I do, and things are somewhat jumbled already. What's got me stymied is how many places to set at my Thanksgiving table if I have several genderqueer guests coming. Do "they" each get one place setting or two?

Let me be clear---not queer, but clear: I could not care less if you want to have sex with a lamp or be called an It or wear spike heels with a codpiece, that is your damn business. It has no impact on my life, and in fact bores me. Be queer or not -- my blood pressure numbers will stay the same. What bothers me is messing with the English language. As far as I am concerned, "they" means more than one, and if you are one person, even with warring sexual personae roiling within, you are still only one person in my book. And FYI, that means no extra dessert.