Lawnmower

Mom called the 14-year-old Boy.
"Son, I have found a lawnmower for you to take apart," she said, showing him the used lawnmower. "I know you enjoy taking things apart, and you've often expressed how you would like to be given more opportunities to disassemble things, so I found this free lawnmower. It doesn't work. It still has some sharp edges, so be careful with those, but if you would like to, I would like to help you take this apart."
The Boy was pleased, and expressed interest in taking apart the lawnmower.

The Boy went to stay with his father and grandmother.
The Father and Grandmother always told the Boy that they loved him.
The Boy's father and grandmother made the Boy feel stupid and incapable, no matter what he did, no matter what he said. It was always wrong, according to them.
Then they would tell the Boy that they loved him.
The Boy returned to his mother and scoffed at the mower.

"This lawnmower is dumb. Taking things apart is dumb. What kind of 14-year-old is given a lawnmower to take apart?!"
"A capable 14-year-old," Mom gently responded. Boy looked at her, not having thought of this. It's difficult to think of yourself as being capable when the people who love you tell you that you're incapable.
Mom smiled. "Being 14 doesn't mean you're disabled."