The theme that runs throughout the movie, or at least one of them, is intimacy. There were scenes in the movie that really moved me. The first was of the brother and sister, twins, at a time when they were in their mid teens, bodies flourishing and growing, boy and girl becoming man and woman. For all those years they shared an intimate bond, particularly as twins, but it was naive, physically innocent. There comes a time though, and there did in this movie, when such an intimacy is withdrawn from us (as parents) or when it's no longer appropriate with each other as siblings.
There's a scene where the father, who's never really had a relationship with his now 40 year old son, reaches and comforts his now adult child by rubbing his shoulder and hair. It was so intimate. I'm sure that are many people we all know who share with their parents no more than a shake of their father's hand and a peck on their mother's cheek on the infrequent occasions when they meet. No matter how old your child, I can't imagine the desire to embrace them, to really hold them, ever leaves you. Time, distance, circumstance, cross words and inhibitions can steal away from us embracing those that we love the most.
I get a lot of emotional response/value from the movies I see, Benjamin Button was the last I posted about, and that affected me for a long time. This hasn't stayed with me as much, but I really enjoyed it. Some may be disturbed by the main theme, but for some reason I could understand at least their motivations somewhat, even with truly 'understanding'.