"Su familia la quiere mucho y, para ser sinceros, ha hecho muchos sacrificios por sus hijos." quote from cloze exercise
I do not understand to whom 'para ser sinceros' refers to. Does it refer to 'su familia' or Eva, the daughter who made the sacrifices?
Why is 'sinceros' plural since it refers to a singular noun, either su familia or Eva?
This sentence doesn't make much sense to me.
I understand the need for para in para ser sinceros to mean in order to be sincere, but I am confused as to why sinceros is plural and to whom it refers.
Using para (and not por) for purpose, goal or objective