I used to work as a chef. I'm healthy weight, exercise well, know how to cook. I love dim sims and once every two years get a craving for tinned tomato soup.
I know how to brew beer, am personally familiar with almost every style of beer available in this country commercially and a few HB versions of styles that are less available. I have conducted and participated in taint sessions and am BJCP certified.
At the moment I am enjoying premixed bourbon and coke and ice cold barvaria longnecks.
Knowing what is good and what is crap doesn't occasionally stop you getting a hankering for crap. People watch shit TV, read shit books, newspapers and magazines, eat shit food, drink shit beer. As long as you don't make it your life or remain ignorant of the world out there, I don't think it's always a bad thing. See it as a challenege, brew something in the ballpark for your brother. Then teach him how to make it.
Summarised as recognising a turd doesn't stop you from sometimes wanting to eat one. You don't even need to polish it. I think not recognising it is the ultimate sin.