I am a citizen of Russia, whereas my mother, a citizen of Latvia, lives in Latvia. Can I apply for a residence permit based on the fact that I am the son of a Latvian citizen?

Yes, the current Immigration Law allows citizens of Russia to apply for this type of residency. You can apply for a residence permit in Latvia (when submitting documents for the first time – for 1 year, for the second time – for 4 years) due to the fact that one of your parents is a citizen of Latvia. It is important that you should prove your kinship with a birth certificate (with an Apostille).