California residency?

I moved to the US when i was 7 and live here for 12 years. First state I lived in was California, Contra Costa county area for 5 year (age 7-12) and then I moved to Texas, and lived in Collin County area (for 7 years. age 12-19) because my dads job. If i go back to Cali am I a resident? I know I'm a resident in TX, but I don't know What happens if i were/wanted to move back because I know theres a age issue.