A twin question

In my understanding identical twins are from the same sack, one placenta, could be 2 umbilical cord, two sacks but still one placenta, and should look alike, with slight difference due to the dna are like clones. i am still curious regarding the test they did in my grandkids, not regarding who is the father but their dna came up exact like clone step by step number by number, and physically they do not look a like, and the doctor always said they were fraternal due to separate placenta, 2 sacks, 2 umbilical cords, inferior and exterior placenta, and you really can tell them apart your know they are brother but not identical.
the place that they did the test said is the first time they saw this in the years of practice, test was done twice, swab. are my grandkids a different kind of identical twin or their are identical twins that don't look alike.

ej. one is darker than the other
one has round eyes the other chinese like
ears one is bigger than the other and there head is shape different.

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Answer 1 / 2

Submitted 162 days ago...

mahalo

Professor (1,186)

If you are asking if twins with near identical DNA can look different then the answer is yes. When talking about genetics there are two factors.

Phenotype: The DNA in all of it's actual pairs and combinations. That is what you say was identical when the doctor checked them.

Genotype: This is the actual expression of the genes or the way that they appear. Which you are saying is very different.

For simplicity, we can use a common example like brown eyes and blue eyes. Brown eyes are a dominant trait over blue eyes. I could go into heterozygous and homozygous genes, but to keep it simple, lets just say that both parents have brown eyes (genotype), but in their DNA make up (phenotype) they have a recessive trait for blue eyes.

B = Brown eyes (dominant trait)
b = Blue eyes (recessive trait)

Bb (mom) + Bb (dad) = BB Bb Bb bb are the possible combinations meaning that they have a 75% chance of having a child with brown eyes and 25% chance of having a child with blue eye.

This is a very simplistic example, but you can see what I mean. Even if their DNA looks very similar even identical, the possibility of those traits being expressed differently is there.

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Answer 2 / 2

Submitted 162 days ago...

di006

New User (4)

The dna test is not similar is exact number by number like if they were clones, according to the people in the dna lab, again not similar , is if they took the copy of one paper and put the name of the other child in the paper erasing the other childs name that is how exact came the test. that is why the lab said they are identical twins.

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