Final answer:
A single gene trait with complete dominance follows Mendelian inheritance, meaning it is controlled by one gene with two allelic forms, one being dominant over the other.
Step-by-step explanation:
If a trait is a single gene trait (controlled by ONE GENE) and exhibits complete dominance, then the trait has Mendelian inheritance. Mendelian inheritance refers to the inheritance patterns first described by Gregor Mendel, where traits are controlled by a single gene that exists in two allelic forms within an organism. One allele is dominant over the other, which is recessive. A person with at least one dominant allele (such as Bb or BB in the case of a cleft chin where 'B' is the dominant allele) will exhibit the dominant trait. Conversely, only when an individual has two copies of the recessive allele (bb) will the recessive trait be expressed. In Mendelian inheritance, each characteristic is distinctly and completely controlled by a single gene, and there is always one allele that is dominant over the recessive allele. This concept is a good starting point for understanding human heredity and helps explain how traits are inherited.