The OP kind of explains it. Coming from the UK, there have been many scare stories where people had (in good faith) not declared minor issues such as a visit to the GP for blood tests for a minor ailment or the fact that a relative suffered from a condition which could be classed as hereditary.

This has coincided with a rise in the number of rejections of insurance payouts because these cases were omitted from the original application. Many, however, have been investigated by the ombudsman and overturned because they were deemed unfair and unreasonable. Unfortunately, the people involved have had to go through hell and high water to get this decision.