"My son and I, we are no longer normal people."
You need to use "kein" instead of "nicht" because you're negating a noun.
Interesting. I thought I was negating a verb--a form of "sein." "We used to be . . . now we are not." I gather this is just not how one does it in German?
"Mein Sohn und ich, wir sind nicht länger normale Menschen" would work. But as christian already pointed out, you can't use 'nicht' to negate the noun. And I'd certainly prefer 'keine normalen Menschen mehr' as the alternative sounds rather clumsy.
Thank you. OK, I think I see where I'm having trouble. Because English uses the same word--not--to negate both nouns and verbs, there is no need to distinguish in this sentence between whether it negates the verb or the noun (not-being versus "not-normal-people").
I'll have to study this a little. Would I be correct in saying that in a negative statement, one would only use "nicht" if the verb is intransitive, but "kein" if it is transitive, because then the negation is of the object?
For example: "Ich lese nicht mehr" but "Ich lese keine Bücher mehr"?
Yes, your example is perfect. You might want to check out http://german.about.com/od/grammar/a/German-Negation.htm