Add image to wrapper for all one-column pages only

I am creating a family genealogy site and am using the Twenty Ten theme for the first time. Some of the pages I am using are created by a family tree plugin and it is working fine but I want a different wrapper image on these pages. I have found the section in style.css and amended it this way after finding the solution on the forum.

LAYOUT: One column, no sidebar
DESCRIPTION: One centered column with no sidebar
*/

.one-column #content {
	margin: 0 auto;
	width: 640px;
}
body.page-id-263 #wrapper {background:url(https://watson.mysilvergenes.com/wp-     content/uploads/2011/06/personBanner.jpg);
}

This works. However, since there are almost 200 pages (one for each member on several trees), I need a way to make this work for all one-column pages without adding each page id separately.

Perhaps the best solution would be to make the single column page the default and then amended the two column pages separately. How would that be done?

Here is an example of what I need for all single column pages. The Watsons site-ancestor profile

Thanks for any help you can provide!