Identical Cousins

Possible or Impossible?

By : Sierra Washington and Hannah Waesch

If two sets of identical twins get married and each couple has a child, could the resulting children be identical?

Based on our studies during this project, we conclude that it is not possible to give birth to identical twins/cousins. There is not enough facts and information supporting that this situation can be possible.

Evidence (:


1) Twins share the same genetic DNA.

- A genetic profile is a set of characteristics unique to the DNA of an individual organism or population.

2) Twins come from the same source (zygote).

3) Identical Twins

- Identical twins are twins that come from a single fertilized ovum and are alike in all genetic characteristics.


1) Twins do not have the same genetic patterns.

- Genetic patterns are the predictable patterns seen in the transmission of genes from one generation to the next.

2) It may be difficult to tell the differences between DNA, but there is definitely differences in everyone's DNA.

3) Fraternal Twins

- Fraternal cousins are twins that were developed from separate fertilized ova. They are genetically distinct and are not necessarily the same sex or similar in appearance.

Interesting Information that led us to our conclusion

1) If one parent has an identical twin, the offspring will share 25% of their DNA with their first cousin.

- If both parents have identical twins, the offspring will share 50% of their DNA with their first cousin.

- Technically, the offspring will only be first cousins but genetically they will be half siblings.

2) It is extremely rare for the probability of identical twins/cousins to be born. There is about 250 cases like this in the world. (Quaternary Marriage)

3) Research shows, identical twins can only happen when they develop from one zygote and form two embryos.

4) There are such things as “double cousins” where a brother and a brother marries sisters, the kids can be closely related as siblings, but not twins.

Sources (: