Science Teacher Explains the Mystery of Mitochondrial DNA Inheritance

Mitochondrial DNA: Why We Inherit It Only From Our Mothers We inherit our genetic material from both parents, but mitochondrial DNA (mtDNA) is an exception, passed down exclusively from the mother. This fact has long been established, but recent research has uncovered rare instances of paternal mtDNA transmission. Zeke Darwin, a science teacher and TikTok educator (@zekedarwinscience), explains this complex biological process in a recent video, using simple analogies to make the science understandable for a wide audience. Darwin highlights the significant size difference between the egg and sperm cells. "Egg cells are some of the largest cells in the human body," he explains, "while sperm cells are some of the smallest." This difference plays a crucial role in mtDNA inheritance, as the sperm's mtDNA, located in the tail, typically doesn't enter the egg during fertilization. However, exceptions exist, as Darwin notes, citing a 2018 study that documented cases of paternal mtDNA in a 28-year-old man. The study, published in PNAS, showed that the paternal mtDNA was only found in muscle tissue, indicating a complex biological mechanism for mtDNA inheritance. The video uses diagrams to illustrate the process, further enhancing understanding. Darwin also touches upon the evolutionary significance of this maternal inheritance, suggesting it points to a shared female ancestor from 130,000 to 200,000 years ago. The video's clear explanations and visual aids make it a valuable resource for anyone interested in learning about genetics and human evolution.