The Switch - S6-E11
Jerry Seinfeld: Don't you know what it means to become an orgy guy? It changes everything. I have to dress different. I have to act different. I'd have to grow a mustache and get all kinds of robes and lotions and...I'd need a new bedspread, new curtains. I'd have to get thick carpeting and weirdo lighting. Of course, I'd have to get new friends. I'd have to get orgy friends. No. I'm not ready for it.
The Switch - S6-E11
George Costanza: Do you ever just get down on your knees and thank God that you know me and have access to my dementia?
Chosen answer: George does mention his brother in the episode "The Parking Space". They actually really never mention anything that contradicts the fact he had a brother though, it just isn't mentioned.