Little boys who play with dolls are not necessarily showing homosexual traits,  they are just playing, especially when they have a sister and its quite normal, if you did not have a brother who was homosexual you probably  wouldn’t even be thinking about this when you are watching your little boy play with dolls, however we do  not know really how much of this orientation is genetically inherited and we certainly do not how much you can do about it as a parent  if it was genetically inherited, turning your child away from the things he want to play in is probably only going to cause frustration, aggravation rebellion and other unpleasant traits so I wouldn’t discourage him from playing with the dolls he wants to play with, help your child just to grow in the way that he is growing and do the best that you can with him, that’s all that I would suggest.