You're not an equal product of both parents' genes. Genomic imprinting, a process whereby only one gene copy is expressed, not only exists but, combined with mutations, may lead to disease.

Not only are alleles inherited from a mouse’s mom or dad expressed in unequal proportions in various cells in the brain and adrenal system—a phenomenon called genomic imprinting—but expressing the ...

“Genomic imprinting is set early during development, and the common dogma was that it is then maintained throughout life across all cell types. Yet, our atlas not only confirms most previously ...