FIL is often sharp with our nephews (aged 2 and 4) and I have heard him say on more than one occasion that they should be "given a good smack". He shouts at them sometimes for being too loud/boistrous/often imo just for normal child behaviour, especially when they are cooped up all day. MIL will be looking after our dd soon. She's only 13 months but I am worried about FIL being too harsh with her. Should we say something - or is it a case of in their house they can set their own rules?