Identical twins and their kids.

[Zoiros]

Problem
Amy and Anna are identical twins, so are Barny and Brian.
Amy and Barny has a child together.
Anna is currently pregnant with Brian’s child.
Anna is afraid that the child is going to be identical/very similar to Amy and Barny’s child.

Our study group answered
The children are going to be officially cousins however genetically siblings.
Are we overlooking something?

[Darby]

That makes sense - genetically all the children have the "same parents."

There'll be epigenetic issues that could slightly muddy it, but no one cares about that...

[Cat]

Your answer is technically correct, by I think you overlooking question posed: "Anna is afraid that the child is going to be identical/very similar to Amy and Barny’s child."
I think your answer should include how much they would look alike in your opinion and your reasons for it.