Final answer:
The blending theory of inheritance is the outdated idea that offspring are a mix of their parent's traits, which was disproven by the discovery of genes and Mendelian inheritance.
Step-by-step explanation:
The idea that heredity depended on all parts of the body producing "seeds" that were collected and transmitted to the offspring is known as the blending theory of inheritance. This concept, which emerged before the discovery of DNA and genes, suggested that traits from the mother and father blended together in the offspring, resulting in a mix of parental characteristics. However, this theory was eventually debunked with the advancement of genetics and the recognition of Mendelian inheritance, which showed that traits are passed down to offspring in discrete units known as genes. Our modern understanding of heredity is founded on the work of Gregor Mendel and is further explained by the chromosomal theory of inheritance, which associates chromosomes with the transmission of genetic material.