Different sized pupils in Toddler

[Jordgaleyx]

Hi, I hope someone can help me,
I have noticed a few times now that my 3 year old daughter's pupils are different sizes, one is bigger than the other, it's not constant only occasionally, sometimes they are the same size however I have googled and worried myself, does anyone have experience of this?

My son has this. They gave him an mri at 10 months to make sure, but nothing wrong, just naturally different. His sister has it a little too so genetic I think.