I just think this is not true. Laura Welch Bush: Biography & Autobiography
IMHO, I think W was influenced by his dad in a lot of areas. Including living in Midland. Not all folks in Midland area share this "amnesty" viewpoint. My relatives certainly do not. And some of them are truly half mexican. Likewise, Laura grew up around Midland and even near El Paso.
I think it was just all about BIG business period
The source for that book was probably Laura. I'll ask my friend where she got this info.