Help finding John Turnbull b:1814 about

[mgscott]

I am trying to help a friend looking for Scottish roots.  Her ancestor, John Turnbull was born in Scotland about 1814 and emigrated to Canada quite young.  She has found his marriage and death certificates in Canada but neither show where or when he was born. 

She has some evidence that John's parents were John D. Turnbull and Sarah Stone. I've done a search of potentials on Scotlandspeople but to no success.  For some unknown reason she feels that her John Turnbull was born around the Borders and perhaps Roxbourghshire but this may be a guess?

All ideas welcomed.  Thanks.