Ds, just turned 2, keeps getting his colours mixed up, particularly green/red and green/blue. I really can't remember when they learn colours, but he recognises all numbers up to 20 and some letters too so I don't think he's a slow learner. It's not a big issue even if he is, but I'm just curious as both my maternal grandfather and my brother are colourblind, and I've heard it's passed through the female but tends to affect males. I don't know whether to correct him or not when he says the wrong colour if that's what he sees. Can anyone help?