Bawdy Double (2nd ed.)

The Premier's adult daughter begins to behave with an utter absence of wherewithal and insight. An Admiral's dreamboat son engages in five years of profligate behavior after his sterling, top-of-his-class Academy graduation.

A doctor called in to examine both scions determines they're mutaclones. Her wife kidnapped and her clinic bombed, the doctor flees across the galaxy - into the stronghold of her antagonists.