Luke is Kenny's son!
People have been talking about how Luke is Carver's son, but that's actually false. Luke is Kenny's son! It seems like he changed his name from Duck or Kenny Jr. to Luke since he's is the type to move on since those names just remind him of his dead parents (thought to be dead father) and his horrible past. Think about it. All the subtle hints with the duck portrait at the cabin and the duck statue at the lodge. When Kenny said "hand me that can Duck." He wasn't talking to Clem, but was referring to Luke. Kenny actually didn't even mean to say that, but every parent has a sixth sense when it comes to there children. I don't even think he knew that he was directing it at Luke. Luke tried to play it off and say "Who's Duck?"
Luke is worried about what his dad has become, but is always willing to stay by his side just like when he volunteered to go with Kenny when Kenny said he needed a hand. Luke cares about his dad and doesn't want anything bad to happen to him. He's willing to stay by his side and help him go through his grief. Luke hasn't told Kenny the truth because he believes that he isn't ready for it, but in due time he will be. Remember that cute little annoying kid that we cared about? We'll it looks like he's grown into a nice young man. Don't worry Kenny! Your son is coming to the rescue! Kenny will be so proud. :,)
You cannot deny the resemblance.
Edit: Guys you don't think I'm actually serious right? This is almost 2 years after the events of season 1. I don't expect 10 year old Duck to be in his mid-20's in 2 years.