No, I don't believe there's a culture of uncles marrying nieces, and besides that she was only 10 years old! I've skimmed this thread and noticed a few "othering" comments, with some people attributing aspects of this crime to (misunderstood) "culture differences". There's no culture where torturing a child is considered, in any way, okay. And as for child marriage, the current minimum legal age of marriage in Pakistan is 18, and child marriage (below the age of 15) has been prohibited since 1929!
IMO, I don't believe Sara's punishments began as discipline. Everything I've seen suggests to me that Sara was a compliant, good child, who did what she was told. She was seen by neighbours doing chores. She didn't alert her mother to how she was being treated on the occasion when her mother reported that she seemed "changed". She made excuses for her injuries and tried to conceal them from her teachers. She did what she was told.
I think we are dealing with a sadist and I believe Beinash was the main culprit. Beinash would have been in High School at the time of Baby P. News stories like that tend to be much discussed with friends and classmates at school, so she must certainly have been aware of it and the case may have left an impression on her. As mentioned in the previous paragraph, I struggle to believe the "discipline" angle, which leads me to question Beinash's narrative of the father being a harsh disciplinarian, alongside the fact that his "confession" does not match the injuries that Sara was found to have sustained. If he'd known the full extent of the injuries, why would he preface his confession with "legally punished"? It would have been blindingly obvious that a burn from an iron and bitemarks etc. would not fit this definition. However, if the father was unaware of the full extent of the injuries, it would tally with him making a false confession at the behest of Beinash.
We know screams were heard from the property when only Beinash was at home with the children. And Sara would have spent most, if not all, of the day with Beinash when she was being "homeschooled" and the two men were out at work. The father and uncle volunteered their dental impressions, whilst Beinash refused. Beinash is the one who was ordering sellotape online. It's faster and cheaper to just buy sellotape in a shop, and I can't help thinking that the father would have chosen to purchase such an item from a physical store whilst he was out and about (driving his taxi). So how involved was he in the day-to-day of what was going on? I also get an impression, from the texts to her sister, that Beinash can be quite devious and manipulative. I mentioned in an earlier post that I suspected one of her texts (about Sara vomitting) was an attempt to cover up deliberate starvation.
So, I think we have one sadistic psychopath (Beinash), a negligent father who failed to protect his daughter (and was subsequently framed and manipulated into confessing by the one person who knew precisely how bad the injuries were) and an uncle (who had less power to intervene than the father and was not even declared as living at the address, IIRC, which may have created additional conflicting issues for him). IMO, I suspect there are likely to be varying degrees of culpability. I cannot believe that all three adults were sadistic. In similar cases, it's usually one perp and others who fail to take action against the perp.
JMO.