A common practice by farmers in the olden days long before the advent of new technologies to develop new plant and animal varieties is selective breeding.
Plants or animals with desirable traits are selected and bred against one another in other to produce offspring that will combine the traits in the parents.
This practice produces offspring with hybrid vigor and has been in use before the advent of genetic engineering where desirable traits can be extracted and artificially embedded in the genome of another organism of the same species but different traits.
More on selective breeding can be found here: https://brainly.com/question/461245?referrer=searchResults
