Missy and teenage boys

We've been observing Missy with other people. She has been friendly to people she met as long as they had a kind word for her. She likes to hear them greet her. Sometimes she would give a warning bark or two but then she would roll over and show her belly or come in for hugs and scritches once someone talked nicely to her. However we did notice her reacting more to teenage boys. The boys we had seen on our walks were on bicycles, scooters or skateboards. When I had them come pet her she seemed to do OK. The only one she was very afraid of was wearing a large backpack and sitting on a park bench. He did not even look at her but was busy texting on his phone. We walked around the boy and she would not get withing 40 feet of him. She clearly wanted to go the other way. This was the most fearful reaction I had seen of her at that point. Missy had met a 6 yr old boy when we went to the groom shop who bounced around and yelled and all she wanted to do was play with him. No fearful reaction. She loved my husband on first sight and was not afraid of either of us. The other fearful reaction she had was to our house cleaner. I had her give Missy a treat and Missy was still afraid of her and gave a semi-growl as she was trying to eat the treat. She didn't want to be petted by the house cleaner. Given that the housecleaner was moving all over the house with cleaning appliances and banging a dust cloth to dust the stairs I didn't attribute it to much other than the nature of her job. All my dogs have eventually gotten used to the house cleaner but they have all barked at her at first.

So that brings us up to today. I hired a neighborhood teen to watch her while I got my hair cut. I wanted to be sure she didn't try to lick her stitches. As usual she was a little nervous when greeting the boy but when offered treats she took them. But she was very wary of letting him pet her and tried to not let him pet her head so I asked him not to. After I showed him how to walk her we came back to our front courtyard where he was going to watch her while I was gone. The teenager had left the treat bag I had given him on the chair. Missy went to investigate and at the same time the teenage reached for it to take it away. Missy cowered down, clearly in great fear. We had not once seen her cower. I spent some more time with them and asked the boy to just sit there while I was gone and throw treats to her.

When I got back I asked how it had gone. Missy had run in circles whimpering and crying for about 10 min. after I left. Eventually she had come to lay down near him and taken treats but she was still reacting fearfully when I got back.

Based on the lack of training I feel Missy came from an outdoor home and had limited human interaction. She seems to view adults as her caregivers and loves to give adults hugs. She is affectionate and does not seem to perceive adults as a threat. However somewhere in her past she has likely been mistreated by teenage boys.