syn·ge·ne·ic 
(sĭn′jə-nēĭk)
(sĭn′jə-nēĭk)adj.
Genetically identical or closely related, so as to allow tissue transplant; immunologically compatible: syngeneic grafts; syngeneic mice.
[From Greek sungeneia, kinship : syn-, syn- + genos, family; see genə- in the Appendix of Indo-European roots.]
syn·ge·nei·cal·ly adv.