Is the normal behavior for my dog?

I just got my 2 year old boxer about 2 weeks ago.
   
She follows me around all the time, I can't leave a room with her right behind me. Sometimes when I sit down she will come up next to me on the couch and stand on my chest, she has also started doing this to my 3 year old son as well. When she does this she is not being aggressive, she just walks up on to my chest. I was just wondering why she does this and if I need to put a stop to it?
   

She's very, very happy to be with you & your son. She loves having a home & wants to be close to you all the time, because she didn't have anyone before & doesn't want to lose you. She now has a pack & 3 year olds are just funny-looking puppies to many dogs. A happy pack is a pack that has a lot of physical contact.
   
This is especially true with newly adopted dogs - when they realize that they have a new home, they tend to be clingy for awhile. Once she settles in & realizes that she's staying, she'll calm down & be less a shadow.
   
However, don't be surprised if, for the next 6 months, you aren't allowed to go the bathroom alone.
   
Remove her from your chest & teach her that she's too big to be a lap dog - sort of slide her off you & onto the floor or next to you on the couch. Teach her not to crowd your son, too. Pat her head when she's next to you & tell her you love her. Teach your son to treat her with respect - no ear-pulling, no kissing on the snout (sometimes accidents can happen); he can kiss the top of her head.
   
Start training her.
   
Note: If she nips your son, DO NOT PANIC. Especially if no skin is broken. This nipping, where the dog lifts skin with its front teeth, is a pack grooming activity. The dog looks like it's chewing on a person, with the very end of its mouth. It's not biting, it's family. (My dog does this all the time.)
   
And be aware that your dog may start treating your son like a puppy, & start herding & supervising him. My dog did this in a previous home (we're Home #4 in his first 2 1/2 years). Since we don't have a 3-year-old, Marlowe is now supervising one of my cats (quite a show).