Answer:
the pleiotropy and epistasis (more info below)
Step-by-step explanation:
Many human traits have dynamic forms of ancestry. We can be regulated by a single gene with several alleles, or by several genes. Further complication can be added by pleiotropy (one gene, multiple effect) and epistasis (gene-gene interaction). A number of hereditary diseases are triggered by defects in one or a few genes. examples: autosomal dominant, autosomal recessive, X-linked dominant, X-linked recessive, and mitochondrial.
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