My husband and I went to an exhibition about the solar system at our local natural history museum. There was also an exhibition for children about the human body with really good explanations how genes work, how our ear works, stuff like that.
We came to the part about the eyes and there was an explanation of colorblindness and the different forms together with the tests. You know - the circles with dots where you have to read the number. Anyway, I forgot why but he started reading out the numbers. And well, he got one of them wrong. Not the test for full-on red-green blindness, but he can’t tell certain shades apart.
In hindsight I had noticed that he sometimes confuses names for colors apart from the basic ones or that he doesn’t like it when I identify an object by its color (e.g. “give me the pink one”). But I’d always chalked it up to German not being his mother language.
I constantly got grades deducted in shop-class for using the wrong resistors (even though my calculation were always right). Even kept arguing with the teacher about how I did’t use the wrong one … but we never put it together.
I only found out a couple of years later during the conscription physical. Then it all made sense …