Not really...
Less than 5 minutes of the movie is actually sexual.
Less than 5 minutes of watching a lesbian sex scene with your parents will be awkward though. I can't imagine wanting that to last longer with the parental next to you.
I finally saw the film today. It left me speechless and wanting MORE. It was fantastic. Natalie is an amazing actress, she should definitely win the Oscars. She just have to.