It is very unfortunate that your niece has no support from her parents, but it is great that you have taken an interest in her and her son. She is fortunate to have you in her and her son's life! From what you describe, your niece could be setting herself up for future behavioral problems with her son if she continues down this path. By resorting to physical punishment and yelling, she could hurt their relationship and the trust between them.
It has been said that "loving your child is not enough". Parents need to love their children unconditionally, but part of that love is to set limits and have expectations. It's also important to follow through with positive discipline that teaches the child, rather than punishes the child. Harsh punishment not only leaves a child feeling powerless and angry, it also creates distance between the parent and child which can lead the child to distrust the parent.
She has most likely learned how to parent from watching her own parents, and from her own experiences as a child. While many of us will parent the way we were parented, parents can make changes and learn new ways of doing things which will bring more harmony into the home. People can change if they are committed to bettering themselves and the lives of their families.
Encourage your niece to praise her son for even the little things he does. It has been said that the ratio of positive to negative consequences should be 4:1, mealing for every consequences the child is given for misbehaving, make sure the child is recieving about 4 times more positive strokes during the course of the day. She needs to catch him being good and let him know how much she loves and appreciaates him.
Your niece would benefit from taking a parenting class. Here at Boys Town we offer Common Sense Parenting classes in many areas of the US. Our parenting website also offers a great deal of information and parenting tips. Our Hotline is also here for parents who are having behavior problems with their children or are needing additional support and guidance. Please let her know that we are here 24 hours, 7 days a week to listen and to help. Our resources are listed below.
Take care and thanks again for reaching out to help your niece and her son!
Boys Town National Hotline