WordNet (r) 3.0 (2006):

blood relative
    n 1: one related by blood or origin; especially on sharing an
         ancestor with another [syn: blood relation, blood
         relative, cognate, sib]

Moby Thesaurus II by Grady Ward, 1.0:

42 Moby Thesaurus words for "blood relative":
   agnate, ancestry, blood, blood relation, clansman, cognate,
   collateral, collateral relative, connections, consanguinean,
   distaff side, distant relation, enate, family, flesh,
   flesh and blood, folks, german, kin, kindred, kinfolk, kinnery,
   kinsfolk, kinsman, kinsmen, kinswoman, kith and kin, near relation,
   next of kin, people, posterity, relations, relatives, sib, sibling,
   spear kin, spear side, spindle kin, spindle side, sword side,
   tribesman, uterine kin