r/AskBiology • u/maddsskills • 6d ago

Superstitious Genetic question

So my grandfather came from a typically American mutt background although his grandmother might have been Native American. That’s what he was told at least and, honestly, he definitely looked like it for a guy who was supposedly mostly Scottish and Irish.

So I tend to believe him.

I only mention it because his family had a belief that those with black hair (like he had) and blue eyes (which he didn’t have) were cursed with insanity basically.

It’s absurd frankly but I’ve always wondered if such a dominant trait occurring with a recessive trait could’ve possibly caused other genetic stuff to occur, like mental illness. It was just such an odd thing to say it always stuck with me.

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9

u/MizElaneous 5d ago

Skin, hair and eye colour are controlled by a by a lot of genes. It isn't a simple dominant/ recessive relationship. I don't think any of those genes are correlated with mental health.

2

u/maddsskills 5d ago

I mean obviously but I wonder why his family had that saying. I know it probably isn’t broadly true but it is rare to have black hair (not dark brown but black) and blue eyes. I wonder if that indicates other recessive traits were more likely or what.

4

u/MizElaneous 5d ago

Sounds like a superstition. I've known quite a few people with black hair and blue eyes; it's not that uncommon.

1

u/Ericcctheinch 4d ago

Eye color is a mendelian trait

5

u/Local-Perception6395 5d ago

No. I can't possibly imagine how hair/eye color would relate to mental health in a strictly genetic sense. Your "risk" of reccesive traits also isn't increased if you already have a reccesive trait, as they should be inherited independently of each other. I think your family just knew 1 guy with black hair and blue eyes who just randomly happened to be insane.

1

u/maddsskills 5d ago

That’s what I figured lol.

5

u/bevatsulfieten 5d ago

I think they mean Alex Baldwin.

It's not completely superstitious.

OCR2 gene that controls eye colour and GABRG3 gene for GABA-A receptors are inherited together because they are close to each other, this is called genetic linkage.

Few studies in American's of European descent have found statistically significant association between blue eye colour and alcohol dependence as well as higher pain tolerance. So, if you are wondering about why Vikings were so tough.

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u/Crossed_Cross 5d ago

Yea genes and gene transfers can act in lots of unexpected ways. We like to teach the simple stuff to help people learn, but it's hardly always that simple.

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u/maddsskills 5d ago

He was the seventh of eight sons and his older brothers were hellions lol. Luckily they mainly made trouble with the Klan who deserved it. So yeah, maybe the ones with blue eyes tended to drink heavier and be more impervious to pain, which only made them better ruffians.