My mother is like that. I'm in the process of coming out to everyone, but I actually came out to my mom about 3 years back. She's lesbian and rather open with me so I wasn't TOO terribly nervous. I came out and said it. She looked at me, said, "Okay, yeah, sure you are" and walked away. When I came out to her again a few months ago, she acted as though she was hearing it for the first time (but listened the second time around thankfully). The denial is strong with this one, yes.
I'm worried my dad is going to be the same way, but I've got a bit of arsenal. When I was in the 7th grade my father and I had a month long battle on whether or not he would let me try out for the boys football team. He ended up not letting me because football "is a boys sport." I wouldn't talk to him for weeks. It literally tore apart our household. I can even remember a time where he made fun of me for "crossdressing" and asked me if I wanted to be a boy (mockingly, which at the time i vehemently denied, cause even at 12 I knew it wasn't "normal"). My worst fear is that my dad will go so heavily into denial that he won't see any of this no matter how I point it out.
But que sera, sera. That's a little ways off, and I've got plenty of support otherwise. I'm thankful to be one of the lucky ones, as I've got a great support system.
Good luck to all of you with parents/siblings/friends/anyone in denial. It's a tough place to be in and at times can be very disheartening. Just remember that at the end of the day, the only person who's opinion matters is your own. Good luck on all of your journeys.
also, oops long post. woah sorry for the wall-o-txt.