If my grandmother and greatgrandmother lived to around 100 and my mother is in her mid 90s what are my odds of a long life?

Good genes. You have good genes but we can not predict how long you will live and your future health.If you avoid being over weight, dont smoke, maintain your health by regular check ups to keep your blood pressure and cholesterol under control, and get cancer screening as recommended for your age and sex, like colonoscopy, pap smear and mammogram etc, you may live till 90 or 100.