How long does the whitening effect on yellow teeth last?

My father had yellow teeth, and I have them too, and even my daughter...

I'm worried about my yellow teeth.

My daughter doesn't drink coffee or smoke, but anyway

It seems to have turned yellow due to genetic factors.

It was fine when I was young, but now that I'm an adult, laughing or talking

It seems like it subtly bothers you when you do it.

So I want to whiten their teeth, but their gums tend to be weak.

I was worried about side effects or how to maintain the whitening effect.

I wonder how long the liver will last.

I would appreciate advice from those who have tried teeth whitening.