They worked out the ratio of the length of the index finger to the length of the ring finger for each child, and compared it with those of 34 of the children's healthy siblings, 88 of their fathers, 88 of their mothers, and a number of unrelated controls that were matched for sex and age.

ECONOMIST: Autism

To sign up, you take a personality test that Fisher designed, which asks you questions about everything from feelings about following rules to your understanding of complex machinery and the length of your ring finger, relative to your index finger.

NEWYORKER: Looking for Someone

Overall, therefore, men tend to have longer ring fingers than index fingers, whereas in women the two fingers are more likely to be of equal length.

ECONOMIST: Autism