Aggressive with toddler?

Question
Hello Dawn-
Please help!  My husband and I adopted a 1yr 2 month old German Shepherd male, just neutered from the kennel.  We have one of our 2 year old grand-children visiting.  When introduced "Duke"(the Shepherd) started nipping at his feet while my daughter was holding the toddler.  This led to Duke biting the toddler's shirt because he wanted to get at him.  Later, we tried the introduction again this way:  We put the toddler in the wagon and went for a walk.  Duke insisted on nipping at the toddler and my daughter stepped in between them.  This caused Duke to nip her in the leg.
Hours passed and the two were not together.  We have a Glass patio door.  Duke was on the one side and toddler on the other.  Duke ran up to the door and grawled, barked and jumped on the door.  
We are nervous and are considering taking him back to the kennel tomorrow because of the safety of or grand children that visit weekly.
Please advise...

Answer
Hi Barb,  It sounds like he doesn't get along with kids.  He acts like he has been teased by kids, just by how he acted at the door.  That will make them aggressive towards kids.  At his age you need to return him as you will not change that behavior.  Hope this helps,

Dawn