I think it is important to distinguish between GMO and Hybrid seeds as they are different. GMO seeds are the Frankenstein seeds were a virus is used to create the genetic change.

Hybrid seeds are simply seeds that are cross pollinated with a different species. In a garden, for example you can create a Hybrid seed of Pumpkin and Zucchini just by planting these plants next to each other. The result is a orange zucchini looking fruit. The same with different types of tomatoes. Sometimes these plants can reproduce but most of the time these plants will be sterile and cannot reproduce. This is why heirloom seeds are the best for the garden and seed saving, when cross pollination is controlled to the same variety you can create a variety heirloom that will thrive in your local environment.