Similar to Floridama, DS understands that people are biased and often uninformed. He understands things like brain plasticity and that even his crazy math skills are some aptitude combined with his passionate pursuit of the topic.
I try to give him unbiasable feedback. I own my own emotional response to something he does and he can place his own value on that: "I'm happy you did X... I'm amazed at how well your work seems to have payed off... I'm impressed you've come so far...." I think sarcasm and lots of joking help, because that keeps him practiced on evaluating the source and intent of a message, and comes naturally to us. I grew up highly uncomfortable with praise and took me many years to overcome self-deprecation or excusing away success. I think some of that was from a survival instinct to not be focused on the wrong side of the stick.
