If Kirk says "I was born in Iowa", that is now canon (part of the history of the show) from there on in. They can't turn round and say he was born in calcutta.
Yes, but what if Kirk was lying when he said he was born in Iowa?
Or he simply forgot?....
...
...It's not so simple, is it?
Point taken.
In The Deadly Years, it could have just been senility. In fact I think the exact dialogue was something like:
"I was born in IowI WANT GREEN JELLO!"
And in STIV:TVH, I'm sure he told Dr. Gillian that only because he wanted to impress her in hopes of getting some nookie: "Hey baby; I'm from Iowa"