if a pair of twins were to have a baby with another set of twins, would the babies come out identical?
In: Biology
They would be genetically the same as siblings born to the same parents. There is an infinitesimally small chance of them being genetically identical like identical twins.
Every child gets half of their genes from the mother and half from the father, but what they get is random. Even multiple children from the same parents are not identical.
If Anna and Alice are identical twins and Ben and Bob are identical twins then children from Anna+Ben and children from Alice+Bob will (on average) have 50% of their genes in common, the same as e.g. multiple children of Anna+Ben. Genetically they are as related as siblings.
Isn’t this called quaternary twins?
Just because the parents are genetically identical doesn’t mean the children will be. Siblings have the same parents and can look totally different, after all. For example my sister and I have the same parents, but she’s white and I’m black. Genetics is a weird thing sometimes. This is the same kind of thing.
A pair of identical twins having children with a pair of identical twins would result in children that look like siblings genetically, despite being cousins.
A pair of identical twins having children with a pair of fraternal twins would result in children that look like they fall somewhere between siblings and cousins. Specifically, they’d look like half siblings staying within the same family. Ie parent A has a child with parent B, and then also has one with parent B’s brother or sister.
A pair of fraternal twins having children with a pair of fraternal twins would result in children that look like cousins genetically, as expected.
Fraternal twins are two children born at the same time, made from 2 eggs, 2 sperm, and had 2 placentas. Identical twins are made from 1 egg and 1 sperm with 1 placenta, it just split into 2 embryos very early on. Fraternal twins just look like normal siblings genetically, but identical twins share the same exact DNA.
Are siblings usually identical? No. Why would they be in this case?
Here is an article on identical twins that married identical twins, and had children. The babies are young in this picture so it’s hard to tell if they will grow up looking more alike.
https://www.today.com/today/amp/rcna17270
Isn’t there a group photo of a couple of bro twins that married sister twins and their families are like all mirror images?
no.
for the same reason that children of the same parents are not identical. Genetically, the children in the scenario you describe would be like siblings.
It has happened where a set of identical twins married another set of identical twins and they both had a set of identical twins and technically all the kids were genetically siblings despite being cousins.
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