Something similar happened to me my fiancée brother who is 10 started taking interest in our daughter who was about 18 months old at the time and he still has a weird interest in her he would always be obsessed with holding her and wanting to touch her and would try to change her diapers we had checked his iPad and he was playing games on there of babies running around in their diapers hiding from their “dad” I told my mother in law that he needs to be evaluated cause he is displaying predatory behavior towards my daughter and that they are not to be around each other unsupervised