Not sure of these black spots on my skin

[Atinosh]

Hi,

Over the last one year, I have started developing these black spots over the upper part of my back as well on the sides of my arm. They are tiny and grow within the skin in small clusters, almost at a distance of hair follicles on the skin. I believe these are pigmentation marks. My dermat says it's hereditary or caused by exposure to the sun and that nothing can be done about it.

I have three questions:

1. Why are these marks showing up? My mother and my sister have it too
2. Will they spread further and get darker over time?
3. What can I do to prevent it and cure it? Would laser treament help or a peel? I've read that with peels, they lighten for a while but come back up again.

Any tip in this regard would be very useful. I am attaching pictures of my arms and my back for your reference.

Some additional details:
Age: 25 years
Diet: Vegetarian

Thanks and regards,
Shonita