A.S.
OK - this is just my opinion, so take it with a grain of salt, but I think they are fine and dad is way over reacting. Is the hair stroking thing something that you to the kids? I do it for my daughter all the time. My 3 yo daughter has a little playmate the same age and they do that kind of stuff all the time. They also fight over toys and aggravate each other to no end some days. They're too young to know anything sexual yet and are just being affectionate in the ways they have been shown. Id get a couple of books about child behavior and show him so he sees its natural because if he ever catches them playing doctor, look out! :)
Good luck!