The person blaming his parents because they tried to do their job of, well, parenting a child with ADHD. I’ve read that psychotherapy is much more difficult when there is no-one to blame. So it might help for him, until he will have his own kids with ADHD and fail in a completely opposite way. I would not recommend anyone to blame parents of neurodivergent kids, as it is a very difficult job to do right.
They fill you with the faults they had, And add some extra just for you.
But they were f'd up in their turn, By fools in old-style hats and coats,
Who half the time were soppy-stern, And half at one another’s throats.
Man hands on misery to man. It deepens like a coastal shelf.
Get out as early as you can, And don’t have any kids yourself.
- Philip Larkin, This Be The Verse