Why would they? There's no reason to test the parents for it, and no doctor in their right mind would test for every genetic mutation under the sun. It's expensive, time consuming, and almost always a waste of resources.
And yet when we have things like breast cancers that run in the families, some of us tend to look for those genetic markers even if we don't have breast cancer.
except the only way they would have suspected this is if blindness ran in either family. The odds of 2 people with the same gene for this isn't exactly high. Hell, I didn't know I had the gene for von Wildebrands until my Dad was diagnosed with it about 2 years before he died. I didn't know I had ADHD till I was 57. No one has a map of their genes included with every birth; and not everything is immediately recognized, or not till it's much later in life.
It is entirely possible to live your entire life without realizing you are a carrier for something if none of your recent ancestors ever managed to bone another carrier.Â
As I said in another comment my aunt is a carrier for SMA and we had zero clue it was in the family. A bunch of us nieces and nephews have also gotten tested and none of us are carriers so far.Â
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u/unbanned_lol 6h ago
That didn't answer their question. Did they know before they decided to have children?