You probably celebrate Mother's Day. And you probably get your mother flowers and other things you don't give your father on Father's Day. Bigot.
Seriously, though, aren't we supposed to believe that there's no significant difference between the genders? Don't feminists, proponents of same-sex marriage, and other people often suggest that it's hateful, mean-spirited, or whatever to treat men and women as if they're significantly different?
Most Americans support state recognition of same-sex marriage, yet the large majority of Americans support having distinct holidays to celebrate motherhood and fatherhood in distinct ways. And everybody or almost everybody who celebrates those holidays does so under the premise that mothers are females and fathers are males. It's not a matter of a two-men relationship, with one having the mother role and the other having the father role, for example. Rather, Mother's Day cards use female terminology ("she", "her", etc.), Father's Day advertisements feature males, and so on.
Since traditions, laws, and other aspects of society are often based on what's generally true rather than what's universally true, all it takes is a general difference between men and women to justify something like celebrating Mother's Day the way we do. Similarly, such gender differences, even if they were only general rather than universal, would justify something like distinguishing between opposite-sex marriage and a same-sex relationship that some people want to call marriage. An opposite-sex couple's romantic relationship is significantly different than a same-sex couple's. Being raised by opposite-sex parents is significantly different than being raised by same-sex parents.
Why is it that Valentine's Day ads are so focused on having men get flowers, candy, stuffed animals, and such for women? Is that hateful and discriminatory? Are flower companies bigoted if they don't divide their flower ads evenly between Mother's Day and Father's Day? Aren't some of these companies that recognize such gender differences surrounding Valentine's Day, Mother's Day, Father's Day, etc. the same companies that are supporting the same-sex marriage movement in some way? Why don't they apply their standards more consistently? Why don't they start evenly dividing their ads for flowers between Mother's Day and Father's Day and see what happens? Even if they lose money, shouldn't their alleged ethical concerns about not being bigoted, discriminatory, etc. lead them to making the decision to lose money rather than promote hatred? Why don't the liberals and others who are promoting nonsense like same-sex marriage put their money where their mouth is and stop being so intellectually shallow and hypocritical? Shouldn't the Americans who support state recognition of same-sex marriage stop celebrating Mother's Day and Father's Day the way those holidays have traditionally been celebrated? Take your own medicine, bigots.