What were Ram Lal and his wife's concern about Bholi? Why did they not about their other children?

Ram Lal and his wife were concerned more about Bholi than their other children because she was the weakest child in the family while her other siblings were healthy. They were worried about her ugly looks because of the pockmarks all over her body and also because of her stammering. They were worried that no one would come forward to marry because of her weaknesses.