Genetics Is Personal — Literally
Of all the topics in biology, genetics might be the most personal. It's the science of inheritance! Genetics tells you why you have your grandmother's eyes, your dad's laugh, or a predisposition to a condition that runs in your family. And one of the most powerful tools geneticists use to map all of this is the pedigree chart.
I'm Dr. Danielle Spice, PhD in Cell and Molecular Biology. Let's break down what a pedigree chart is, how to read one, and why they matter.
What Is a Pedigree Chart?
A pedigree chart is a diagram that maps the occurrence of a trait or condition across multiple generations of a family. Think of it as a family tree — but with a scientific lens. Instead of just showing who's related to whom, a pedigree tracks which family members have a particular trait and helps scientists figure out how it's being passed down.
Pedigrees use standardized symbols:
- Squares represent males
- Circles represent females
- Filled shapes indicate an individual who has the trait or condition
- Horizontal lines connect couples; vertical lines connect parents to children
How Do Geneticists Use Pedigrees?
By looking at the pattern of filled and unfilled shapes across generations, geneticists can determine the mode of inheritance — that is, how a trait is being passed from parent to child. Common patterns include:
- Autosomal dominant: the trait appears in every generation, in both males and females
- Autosomal recessive: the trait can skip generations; carriers don't show the trait but can pass it on
- X-linked: the trait appears more often in males, because it's carried on the X chromosome (males are XY while females are XX)
This kind of analysis is used in medical genetics to assess risk, in research to study inherited diseases, and in animal breeding to track desirable traits.
Pedigrees as Art
Here's something I love: pedigree charts are also beautiful. The clean geometry of squares, circles, and connecting lines has an elegance to it — which is exactly why we, Dr. Spice and her fabulous artist and genetic counselor collaborator, Claire Newman, turned them into art.
The Pedigrees collection at Science with Spice features custom pedigree-style prints and digital downloads that celebrate your family in the language of genetics. Whether it's a couple, a family with kids, or a household with beloved pets (like Dr. Spice's family), these prints are a unique and meaningful way to represent the people (and animals) you love.
Check out the Couple + Puppy Framed Pedigree Poster or browse the full range of digital download pedigrees — perfect as a gift or a keepsake for your own home. Don't see the pedigree that fits your family? Fill out Dr. Spice's contact form for a custom design!
Want to Go Deeper?
Genetics is a rabbit hole in the best possible way. If you want to keep learning, tune into the Science with Spice Podcast where I break down topics like this in plain English — no lab coat required.
And if you're shopping for a science lover, don't miss the Science Merch collection for apparel, stickers, and accessories that celebrate the nerd in all of us.
— Dr. Danielle Spice, PhD
About Dr. Spice →