My ancestry composition results turned out differently than what I expected.

People generally know about their ancestry mainly based on their family trees that go back several hundred years. The DNA, however, can help us trace back ancestors who lived tens of thousands of years ago. As many groups broke apart from the common ancestor, populations among those in the vicinity tend to share lots of genetic data. As a result, your ancestry composition could result from the migration paths of humanity. 

DNA is also passed down randomly from parent to child. Although your parents have passed down halves of their genes to you, the ratio of the genes from your grandparents may be lesser. The DNA you inherited directly from your ancestors seven generations ago is believed to be less than 1% of your total genes.