Final answer:
Before DNA testing, genetic relationships were inferred from phenotypic traits, often leading to inaccuracies due to convergent evolution. DNA fingerprinting revolutionized this by analyzing matching genetic markers to establish familial connections, reinforcing the Chromosomal Theory of Inheritance and the concept of common ancestry.
Step-by-step explanation:
Prior to the advent of DNA testing, assumptions regarding close genetic relationships were often based on physical characteristics and the understanding of inheritance patterns. However, these methods were sometimes unreliable due to the potential for convergent evolution, where unrelated species evolve similar traits. With the development of DNA fingerprinting, a more accurate assessment of genetic relationships became possible.
To establish that a child is related to their mother and father using DNA fingerprinting, the child's genetic markers must match certain markers in both the mother's and the father's DNA profiles. The fact that DNA sequences are more similar in more closely related organisms is evidence of common ancestry. Research like the Chromosomal Theory of Inheritance has provided substantial evidence that DNA is the source of heritable information, supporting claims like the out-of-Africa theory of human evolution.