Question about my () sisters behavior?

I am 17 right now and I can definitely see your perspective of things. My aunt who is was in the almost exact situation. She was fine before, I never even knew she was gay until I was about 9. I went on a trip about 12 hours away from home with my aunt, grandpa, step-grandma, brother and my aunts girlfriend. My brother stuck me in the car with my aunt and her girlfriend. The whole way they kept kissing each other, talking about what they were going to "do" to each other etc. At the time, I was confused and uncomfortable. However, I came to accept it after 2 years, with my mom explanations and understanding. My advice is to talk to your sister and explain to her that what she does is inappropriate. If she takes it the wrong way, then I would limit the time spent around her with your kids. I am all for gay rights and all but I do not think it's right, regardless of ual preference, to subject younger kids to seeing such things. Good luck!