popa
1. the effect of the yichus upon the person may not be apparent until there is a time of difficuly and challenge, which you may not yet have had the opportunity to observe.
2. could be its like a recessive gene in a sense and may not manifest itself visibly in this person but could become revealed in her children.
3. it takes a long time to get to know a person, certainly much longer than the time spent together before marriage