Why lie about your and your parent's background?

I was proudly informed by my spouse before and during the marriage that my father-in-law worked and retired as a Taiwanese government officer, who merited his own chauffeur to bring him to and back from work; naturally, I believed my spouse, although there were times when I seriously question his stated background given the lifestyle choices he made.  Recently, the investigators my friends hired on my behalf were able to obtain a copy of my spouse's birth certificate, whose English translation stated plainly that my father-in-law's occupation was that of a laborer.  Furthermore, it indicated that my father-in-law is of Mainland Chinese origin while my mother-in-law is a native Taiwanese.  This is a huge and shocking surprise to me as my spouse has always verbally [and loudly] maintained his pure Taiwanese heritage.  Below is a photograph of the certified birth certificate that the investigators obtained for those readers needing proofs.