Can someone explain chances of 4 kids with blue eyes when one parent is brown eyed?

[Korner]

Dsister (blue eyes) has 4 kids with BIL (very dark brown eyes almost black). All 4 kids (7 - 3 yo) have bright blue eyes.

BIL is Sikh Punjabi. Apparently has no history of blue eyes but says some second cousins have green eyes - not common but not unusual. My family all pretty much have blue eyes.

This has to be an anomaly. Just curious as the discussion came up at baby group today. Learned that it should only really be 50% likelihood of blue eyes if one parent has brown eyes and the other
blue.

I have one of each (brown and blue) despite DH being green eyed. I’m also blue eyed.
Genes are very interesting!

So, you both must have 1 brown eyes gene (dominant) and 1 blue eyes gene (recessive). Your children could have either brown or blue eyes. Brown is the most likely. They have a 1 in 4 chance of having blue eyes.

Thanks for the science lesson! Very interesting.

Eye colour is complicated- especially when you add in green, and consider race...but simplistically....
Let's say there is one gene for eye colour, and you have copies that gene. Each copy can either be blue or brown. Blue makes no pigment but brown makes brown pigment which overrides the blue.
A blue eyed (adult) has two copies of the blue gene.
A brown eyed adult can either have two brown or one blue one brown.
Then each parent gives one gene to each child.

So in your case they would always get a blue from mum. And could get blue or brown from dad....so 50:50

The chance of 4 in a row is 1 in 16

BUT

Childhood eye colour doesn’t always stick.
The brown pigment develops with age...just like in blonde haired children being brunette as adults. My parents were both blue eyed as children and Hazel eyes as adults. My sister has grey/blue eyes and I have hazel.
Both my children have grey/blue

The genetics in a punjabi person may be slightly different with more and different genes than in a white European person

So what does it mean when some posters are saying there is more than one gene at play? Sorry dropped Science after GCSEs!

I have dark brown hair and eyes.
DH is light brown haired and hazel eyes.
Our ds1 is blond and blue eyed. Was a surprise when he was born...

Yes but at the start the odds of getting 21 in a row are much lower.

Met a local in Kenya, yes African, lots of Indians live there too, that had blue eyes. He told me his mum and 4 brothers had blue eyes too.

One world! Love it.

Can two parents with blue eyes have a brown eyed child then?

All four children have blue eyes (one slightly green) and DH has very dark brown eyes, whilst I have blue.

So the mother has 2 blue eye genes and the father has 1 brown, 1 blue or possibly green (eye colour genetics is complex with co-dominant genes). Each child will inherit a blue gene from the mum and either a brown or a blue/green from dad. Each conception is independent and the colour of an older child's eyes has no influence on future conceptions. It'll be 50/50 each time blue vs brown. Exposure to UV also influences eye colour cells which is why colour often changes in very early life.

I have blonde hair and blue grey eyes. DH has black hair and hazel eyes (half Italian).
DS1 has blue grey eyes and blonde hair and DS2 has blue grey eyes and black hair.

I’m Asian with brown eyes and my husband is Caucasian with blue eyes and both of our kids have light blue eyes! Where I’m originally from was also a Dutch colony at some point in the past and there is Dutch blood on my mothers side so presumably the blue eyed gene was just hanging around waiting for another!

I am blue eyed and ex is very dark brown eyes, we have 4 dc. Two have blue eyes, one has grey/green and the other has brown.

Green eyes aren’t that unsual in south asians, I’m South Asian, I have green eyes, blue eyes are also becoming more common due to sexual violence during British rule and partition.

If you're going by what you learn in science class, no. In real life, yes. Eye colour in science class is a form of "lies to children". It simplifies the concept to make it easy to understand, but the reality is more complicated.

This^
it happens.

I have green eyes. The whole of my family have bright blue eyes, except my gran, me and two cousins (out of 9 cousins) who all have green eyes.

I have had people tell me that it just isn't possible that my family have such clear blue eyes.... but there it is.

My 4DC also have bright blue eyes. But so does DH, and his entire family. I had hoped that one of mine would have green eyes but it wasn't to be. Let's see how the grandchildren turn out...

https://www.nature.com/articles/s41433-021-01749-x

I don't know the full detail but genes carry the code for making the pigment(s) that give your eyes their colour.
So you could have a gene at place 1 that codes for brown pigment, and you can either have 0, 1 or 2 copies of that.
But another gene at location 2 could also make brown.
And then another at locations 3 could make more of a green.....combined with no brown would give bright green, combined with brown would give Hazel.
Other genes can also switch the genes for eye colour on and off which plays a part.

My cousin is mixed race with green eyes and has a 1 year old with blue eyes. The babies' mother is mixed race and has brown eyes, but her mother has blue eyes. Its a recessive gene

My ex and I have brown eyes.

Our children’s eyes are brown, blue and green which has taught me that genetics is a lot more complicated than I thought.

We both have a blue eyed parent so I assume that the grandparent’s genes played a part here.

I have dark blue eyes and my Dh chocolate brown, ds had the same colour as dh. DD eyes are an amazing mix golden/hazel/grey they used to change colour from one day to the next.

I have 4 children, my eldest is red haired and brown eyed and my second is blue eyed and blonde, I have green eyes his dad has brown. My youngest 2 3rd is blue eyed and dark hair 4 th dark curly hair and brown eyes their dad was dark haired (bald now) and blue eyes. So a bit of a mix up my bil insinuated that my youngest wasn’t his dads due to his dark eyes. 👀

You could toss a coin 50 times and it might be heads every time. Statistically it’s more likely to be heads only half the time but it’s not impossible for it to be heads every time.

My parents are green and blue eyed. I'm brown!!
Dh has brown, our kids are brown, brown and green eyed!!
It's much more complex than people think.