Like everyone born with their own skin
color similar is with teeth. Generalised slight yellow teeth are normal
but if you have gross yellow or brown patches on your teeth that also can be divided by two types one is stains present outer surface of your teeth and second stains present inside surface of your teeth both of the types have different treatment approach for that consult dentist
and kindly refrain from brushing too hard on your teeth as it will lead to early wearing of your teeth surface.