While I've never encountered any comments that support or verify your conclusions it does raise concerns. I'm guessing the answer is I'm not sure. I do harvest seeds from my established perennial plants and winter sow them. In addition, some of my prolific perennials self-seed* but so far all offspring are identical to the parent plants. Like other ideas, I'm sure there will be multiple comments that lean one way or another.

* Great blue lobelia is growing up through my breezeway concrete this year and has bloomed for a couple of months. Columbine and Black-eyed Susans have self-seeded around my garden. I simply enjoy them.

http://www.as.wvu.edu/~kgarbutt/QuantGen/Gen535_2_2004/Inbreeding_Plants.htm

If you want to do more reading then do a Google search for "inbreeding depression in plants". Certain vegetables are more susceptible than others.

Rodney