I failed as a teacher

Yesterday I visited my local evil government house of mail (a.k.a., the post office).  While waiting in line, I overheard a young boy behind me asking his mom, “But I don’t understand how DNA works.  I don’t get it.”  I glanced back and smiled at him and his mom, impressed that a boy that looked so young would know anything about DNA.  His mother explained patiently that she didn’t know and advised him to ask a science teacher. 

Cue the superhero music!  Science teacher to the rescuuuuue! 

I boldly turned around again with my brightest smile, proclaiming, “I’m a science teacher!” 

The boy, not impressed, asked, “Are you a scientist or a science teacher?”  (At this point I’m sure someone with acute vision could see my ego deflate just a bit.)

“I’m a science teacher.  Is that ok?”

“Well, I guess.  My science teacher really loves science.  She has all sorts of weird stuff in her room.  Like, she loves science.”

“Oh, that’s cool.  How old are you?”

“Nine.”

“Go ahead,” said Mom.  “Ask her your question.”

At this point I was prepared to explain that our bodies are made of lots of teeny tiny cells, and inside each one is a chemical called DNA that tells the cell what to do.  Instead, the question I got was much more specific. “Ok, how does the DNA say if you’re a boy or a girl?  I don’t get it!”

Instantly, since I teach high schoolers, images of sperm cells, egg cells, chromosomes, and so on go tumbling through my mind, and all I can think of is sexual reproduction.  My jaw drops a little bit. 

“Um,” I stutter to Mom, “I’m not sure how to explain that to a 9 year old.”