TIL I cheated on my wife when she had… wait a second. /s

That’s not true at all. Blue eyes needs two recessive genes where Brown eyes only need one recessive gene. So you can have parents where both have brown eyes but they both have the dominant gene for brown eyes and the recessive gene for blue eyes. Then if both recessive genes are passed on to a child they will have blue eyes.

Of course there’s a few more complications to this as human eyes aren’t predicated on one gene, but it’s a good enough simplification.