Deadlier by the Dozen — Marcia Colette

"Trust no one. Not even yourselves." Put up for adoption at seven-years old, history teacher Mackenzie Lawson has spent the last twenty years dreaming of meeting her family again. However, her hopes to rekindle old memories and find closure have hit one hell of a snag. A hundred-year-old curse placed upon her relatives has begun, unleashing a dozen of her doppelgangers who want her dead. Their purpose is to infiltrate her family and kill everyone in sight. To exact revenge for a wrong that happened more than a century ago. Mackenzie must find a way to get rid of her psychotic doubles or risk having them go after her loved ones. However, each doppelganger kill causes her blood pressure to skyrocket to dangerous levels. This and more attract the attention of a mysterious mutant with patchwork skin who volunteers his services...but leaves out the part about it being his job to destroy the source of the doppelgangers starting with her. Mackenzie needs to figure out where his loyalties lie before DEADLIER BY THE DOZEN becomes deadlier by thirteen.