People who have white teeth, is it natural?

I often see people with the whitest teeth and I wonder if it’s because their teeth hygiene is just really good or if they use products like teeth whitening strips. Because my teeth are not very white but I have always brushed them twice a day with an electric tooth brush so I’m a bit confused what I am doing wrong. Maybe it’s because I have coffee / soy sauce which can stain teeth/ need to floss more(?) idk