You’re Not 50% Mom, 50% Dad Like They Told You
Good thing, too, because you’d probably be dead if you had equal doses of their genetic instructions
I was gobsmacked to learn that who I am, is not, in fact, composed of half Mom and half Dad. Neither are you. Those high school biology classes that slogged through Mendelian inheritance now feel like a sham, as if I had lost the shell game.
Gregor Mendel, the father of modern genetics, began the body of research that later scientists, including Theodor Boveri and Walter Sutton, expanded to arrive at the chromosome theory of inheritance. Each offspring receives 23 chromosomes from Mom and 23 matching chromosomes from Dad. Fifty-fifty right? We’re frequently reminded of this fact by gushing relatives. You said that just like your father. You smile just like your Mom.
You do have equal numbers of genes from both parents, but that’s not the whole story. It turns out there’s a stop code, running interference inside you, called imprinting. Imprinting is a process that basically flags the gene, so it becomes a mere placeholder, never contributing to the offspring’s development. So if Mom carries all the stop codes, she has fewer expressed genes — those that actually make stuff happen — in the end product, which is you. Same if Dad holds the stop codes.
