What do the " * " or " - " besides each gene mean?

If you see a "-", that means the variant you carry for that gene has no effect on that particular trait.

A "+/*" means moderate effect, and "++/**" means strong effect.

For example: ACTN3 ** in the power section of the reports indicates that the ACTN3 variant carried has a strong effect on power production, whereas ACTN3 -- would mean that variant does not contribute to power.