Plus a database of genetic samples is a tempting target for data theft, and identity verification (by health insurrances, employers, for example). the UK record in keeping data secret has suffered last year.
but not only big coups, but cinstant minor level of data abuse is a concern, plus the appetite of lawmakers may become so intense that first they collect the data on basis of one set of laws, and when the database is ther and is filled, the legal basis gets chnaged and criterions for using it become softend up.