If you ask me, it’s never too early to learn something.
My little girl asked me why I have brown eyes while she has blue eyes. I told her it had something to do with the DNA that she received from her parents. (She and her brother are well aware that they each have half of my DNA and half of their father’s.) But I thought I could go a little further with this. Hence, a lesson in the Punnett square.
Though I didn’t use Punnett squares to attempt to explain dominant and recessive patterns of inheritance, I did think that working through a few Punnett squares and making some connection to genetics and DNA would be helpful in her understanding of science later on. (I recall learning Cartesian coordinates in school and thinking how easy it was because I grew up playing Battleship.)
Anyway, above are the Punnett squares my four-year-old daughter and I worked through together. She picked the letters and the color and I helped her fill in the squares. She did the last one almost entirely on her own.
UPDATE: I wrote this post more than two years ago. I was inspired to post it here because my son, 6, asked me the same question that she asked: why does he have brown eyes while his twin sister has blue eyes? This time I did attempt to explain dominant and recessive genes while working through a Punnett square. Not sure how much he will retain, but at least the neuronal spark will be there when he learns about it in school.