Francis Galton's Twin Studies

10 Questions

What was the probable difference between the twins of the first group and those of the second group?

Identical vs. fraternal twins

Galton's study found that identical twins were affected by ordinary differences in current life.

False

What was a common cause of differences in disposition among similar twins, according to Galton's study?

Serious illness or an accident

Both members of a pair of twins developed a toothache in the same _______ at about the same time.

tooth

Match the following characteristics with the type of twins they are more likely to describe:

Identical twins = Very close resemblance in physical characteristics Fraternal twins = No more alike than brothers and sisters

What was Francis Galton's chief object in studying twins?

To determine whether similar twins become unlike as a result of a difference in environment

Galton's study of twins was based on his own observations.

False

How many pairs of twins did Galton obtain information about?

35 pairs of similar twins and 20 pairs of non-similar twins

Galton believed that there were two distinct types of twins, one of which developed from a single ______ and the other from two separate ova.

ovum

Match the following descriptions with the type of twins:

Similar twins = Difficult to distinguish one from the other by their appearance Non-similar twins = No more alike than brothers and sisters in general

Study Notes

Twins: An Early Study

Studies of twins have been valuable tools for examining the complex influences of heredity and environment on human characteristics and behavior.
The first scientific attempt to study the mental abilities of twins was made by Francis Galton, who was interested in the relationship between heredity and environment.

Galton's Research

Galton's chief object was to determine whether very similar twins become unlike due to a difference in environment, and whether unlike twins become more similar due to living in the same environment.
Galton believed that there are two distinct types of twins: one developed from a single ovum and the other from two separate ova.
He obtained information concerning 35 pairs of very similar twins and 20 pairs of less similar twins through correspondence.

Similar Twins

The similar twins were reported to be so closely similar that it was difficult to distinguish one from the other by their appearance.
Most of the facts obtained relate to their very close resemblance in physical characteristics, such as:
- Both members of 7 pairs suffered from the same physical ailment.
- Both members of 1 pair developed a toothache in the same tooth at about the same time.
- Both members of 1 pair were afflicted with ophthalmia and had attacks at about the same time.
- There were 2 cases of similar insanity.
- 11 pairs said that they had similar associations of ideas.
Differences in disposition were noticed in 19 pairs, often caused by serious illness or accident.

Dissimilar Twins

The unlike twins did not become more alike as a result of their similar environment.
Little detail was reported concerning the dissimilar twins, except that some reports of their differences indicated that they were no more alike than are brothers and sisters.