The West Wing, Season Three

Leo:
I'm an alcoholic. I don't have one drink. [pauses] I don't understand people who have one drink. I don't understand people who leave half a glass of wine on the table. I don't understand people who say they've had enough. How can you have enough of feeling like this? How can you not want to feel like this longer? [pauses, sighs] My brain works differently.

...

Jordan:
I don't understand how you could have a drink. I don't understand how, after everything you worked for, how on that day of all days you could be so stupid.

Leo:
That's because you think it has something to do with smart and stupid. Do you have any idea how many alcoholics are in Mensa? You think it's a lack of willpower? That's like thinking somebody with anorexia nervosa has an overdeveloped sense of vanity. My father was an alcoholic. His father was an alcoholic. So, in my case...

Jordan:
[nods] Ain't nothin' but a family thing.