Delighted because she was glad to see her fraternal twin so happy.

And resentment, doubt's fraternal twin.

However, Galton did not propose the comparison between identical and fraternal twin resemblance which is the essence of the twin method.

After all, there had been no fertility treatments and the only multiple birth family member was her grandmother, a fraternal twin.

For the Dutch study, researchers tracked 839 identical and 1,164 fraternal twin pairs from the age of 3 to the age of 12.