These cracks are signs of foundation settling. How severe is the million-dollar question.  Will this scare a buyer?

Will the buyers lender make a loan on the house? Is it best to call a foundation repair company to check it out?

Is this a bit like having the fox guard the henhouse? There are other options you need to consider. 

I have owned and lived in houses with severe settling & have sold many such houses over the last 40 years. 

I will be glad to view your house & give you all your options.