The original article (by way of Freakonomics):

Finger Length Predicts SAT Performance

The cliff notes:

• In utero testosterone promotes development of the areas of the brain responsible for spatial and mathematical skills. It also makes your ringer finger longer than your index finger.
• In utero estrogen does the same for verbal skills, and makes your index finger longer than your ring finger.

Thus, the ratio of ring-finger-length to index-finger-length is supposed to be a predictor of the relative math/verbal SAT scores.

Even if you are home schooled, it may be a good idea to take the SATs when you begin applying to colleges. To find some other standardized tests you may consider taking you should read some free home school resources. One of the cons of homeschooling is that potential colleges don’t have as many records about a students performance as a public school will have.