It's an interesting point that I have never really considered. I do recall being deeply moved by the siblings in Secret and Lies, perhaps because it did bring to mind the relationship between my brother and I. I've always found siblings to be an interesting phenomenom - I don't mind meeting other people's parents, but there is something intimidating and fascinating about meeting their sibling.
As for the point you make about brother/sister relationships often being sexualised on film, it is something that frustrates me enormously. I think the When Harry Met Sally conundrum rings true to a large degree when applied to film - men and women, according to Hollywood, can't be just friends. I would also say that
equally, female relationships are often sexualised in a similar manner. Which is why I would take contention with your comments above about Father and Son having a homoerotic quality. I haven't seen the film, so I can only go by what I have read about it, still photographs, and my experience of other films. I recently saw "Nathalie," which is a story about a middle aged woman's relationship with the prositute she hires to trap her philandering husband.
Although it wasn't a great film by any means, it was incredeibly refreshing in it's portrayal of female relationships and the human body. For a large part of the film the audience is lead to believe that the middle aged woman is getting her kicks from the stories "Nathalie" tells her about her sexual encounters with her husband. At one point, Nathalie even accuses her of such. There is a feeling of inevitability that their relationship is leading to a lesbian relationship. However, there is a moment in the film that changes our view of the middle aged woman completely. We find out quite far into the film that she is a gynaecologist, and it is a quite shocking moment (refreshing that for once it is the counter of sex that is shocking). It forces a complete reevaluation of our understanding of her, and forces us to see "Nathalie" in a more human light (not desexualised, but humanised) whereas before we were almost encouraged towards voyeurism. Yes, there is substantial nudity and discussion about sex but, the film shows us, the human body is much more than a sexual object and physical intimacy does not equate with sexual intimacy.
Which is where I return to Father and Son. The portrayal of flesh on screen always has the potential to be erotic (which reminds me of a moment in Code 46 where a girl is asked to "tell me something about yourself" and she reveals she has a fetish for freckles: "it's like being dressed but naked," there "is no pornography for freckles" and she considers Anne of Green Gables "an erotic classic") but i think there is a dire need to learn to watch images of the body without eroticising them. Just as there is a dire need to portray male/female relationship without sexualising them or making them into a love story. I think this is especially important for men, particularly (in the UK) with the paedophelia hysteria that has resulted in such strict child protection laws that two people have to accompany a child to the bathroom and childcare workers not being allowed to come into physical contact with the child (no hugging). I remember an American male friend of mine told me a story that he was in town and there was a kid in a pram who was playing and smiled at him so he smiled back and the mother "flipped out," and started hitting him and shouting "don't look at my child."
It's time we reclaimed the look as something non-sexual. I think cinema has needed to for a very long time (especially since Tania Modelski's article highlighted the sexualised connotations of the cinematic gaze). I think reviewers have a big role to play in this. What do you think?