Weiss is inquiring whether the family medical history is an imperfection that must be revealed.
Withholding information concerning an inability to have children is certainly a mekach ta’us.
He was also aware that they were hiding this information from the prospective groom. There are two categories of negative information, imperfections, that one does not need to reveal.
The same would be true should the male be unable to have children, since the assumption is that people of childbearing age marry intending to bear offspring from the marriage. They are information that the other party could find out on one’s own, and information that is not significant.
In shidduchim the same rule is true: Subject to some exceptions, which I will explain shortly, one must notify the other party of information that might concern them.
Hoping that no one takes this personally, I will refer to this type of negative information as an “imperfection.” For example, Mrs.