Only about 1.7 percent of donkey pregnancies result in twins.

In identical twins, if one has autism, 90 percent of the time the second will also have it.

Those traits which are partly inherited will be significantly more similar in identical twins.

There have been many studies highlighting the development of language in twins compared to single-born children.

The influence of heredity is best studied in genetically identical twins.

They can also run counter-rotation for installation in twins.

Another instance occurs in identical twins, one was diagnosed at seven months while the other is not affected.

However, left-handedness is more likely to occur in twins than in single individuals.

Left-handedness in twins occurs at a higher frequency which is 17%.

But for all the interest in twins, the wisdom about rearing them keeps shifting.