My cousin sister is 8 years old, from last 7-8 months I have observing different changes in her behavior. She do not gell up with kids at school, apart from that, she have even started getting jealous with the others, if her parents give attention to some other child, though she is the only child. As per what I have observed, the jealousy or insecurity she faces is with the child of same gender (ex. If her parents gifts anything to any girl, she starts crying loud, or even if they talk to any other kid politely, even then there is a trouble.(i have not seen the same for the other sex). I am very much worried because few months back, it never happened & now this thing is at its pace.