Back-to-School: Genetics 101

Our Hero
Gregor Mendel, an Austrian monk and biologist, worked out the pattern of inheritance of various traits. He showed that a “dominant” trait is one that always shows up in offspring while a “recessive” trait is one that is masked by a dominant gene.

Update: If you took this quiz before 10 a.m. PST on Monday, September 10th, we neglected to capture your name and email address. We sincerely apologize for this oversight. Please fill out the quiz again and this time you will be prompted to enter your name and email. We’ve extended this quiz through 11:59 p.m. PST September 16th to give you plenty of time! 

Pop quiz.  Who was Gregor Mendel?

If only hazy visions of pea pods come to mind you might want to buff up on your biology.

Learning about genetics isn’t just for high schoolers and college students — it’s an interesting topic of exploration no matter what your age or profession.

We’re going to help you with a quick primer and links to some of our online educational videos found on our website and at the Khan Academy. And to make sure it all sunk in we’ve got a quiz at the bottom of this post.

What Are Genes?
DNA contains the instructions for making you and takes the shape of a twisted ladder, having two parallel, but complementary strands. There are four letters to the DNA alphabet — A, T, G and C. Human DNA is organized into two pairs of 23 chromosomes and chromosomes are further organized into short segments of DNA called genes. If you imagine your DNA as a cookbook, then your genes are the recipes. Written in the DNA alphabet, the recipes tell your cells how to function and what traits to express.

Where Do Genes Come From?
You were gifted with a set of 23 chromosomes from your mom and a set of 23 chromosomes from your dad. Twenty two of the pairs contain the same genes on each chromosome and are called “autosomes”. The remaining pair is composed of the “sex chromosomes” and isn’t necessarily identical — females typically have two X chromosomes and males have an X and a Y.

What Are Phenotypes?
Slight variation in your genes is part of what makes you unique. Your observable traits, also known as your phenotypes, result from interactions between your genes and the environment. Differences in some phenotypes, like height, are determined mostly by genes. If you have short parents and grandparents, you probably don’t tower over your peers, though environmental factors like a healthy diet might give you a little lift. The influence of genes on other traits, such as your personality, is less well understood.

Did you get all that? Take our quiz and find out! Prizes will be given to a random selection of people who answer all questions correctly (perfect for buying that genetics textbook on your wishlist). Good luck!

Update: This quiz is officially over! Check out the answers here.

You have now completed the entire 23andMe Genetics 101 course, the second in a three-part Back-to-School educational course series! Click on the certificate below get a larger image which you can print out and display it with pride.


Want to continue your education? Learn about your health and ancestry with 23andMe. Not yet a customer? Visit our store.






  • Dylan Gunn

    The study of genetics is an incredibly important field.

  • David

    I filled out the form, but it never asked for contact information. Does that mean I failed? :)

    • http://23andme.com Shwu

      Hi David,

      Thanks for noticing an important piece that was missing in our original quiz form! We’ve updated the quiz to include a place to provide your name and email address, and are extending the quiz deadline through Sunday 9/16. Please do enter the quiz again for a chance to win!

      We’d give you extra credit if we could, but your chances of winning still depend on getting all of the answers right and how many people enter. :)

      Thanks again!

  • Rhea

    this was a great video.

  • http://n/a Mary Yamada

    Were the videos partly verbal? Any closed captioning that I didn’t see?

    Thanks.

    • BethannH

      Hello Mary,

      The videos have audio but they don’t have additional closed captioning. Please try playing them again!

  • http://obese-starving-artist.tumblr.com Ines

    One great thing about the video “Where do genes come from?” is the diversity. Race/ethnicity mixing is not new, but it’s good that it’s finally getting attention from scientific communities, even in short videos such as this. Part of the interest in 23andme is finding genetically similar people and populations, especially for people who do not have much information on their backgrounds.

  • lamed vav

    i could not find Lesson Two on SNPs.

  • https://ondemand.thefitfem.com/OnDemand.aspx Online Gym

    Great article I agree The study of genetics is an incredibly important field. I’m a big believer that gene therapy will be a huge in the future. Unfortunately it will take time to get us were we need to be. I too I’m interested in watching more videos of this.

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