Heritability for innate ITs such as i) total cell number (EOS and NEU), ii) leukocyte subsets (CD16 + CD2 + cells, CD16 + CD172Acells, CD16 + MHCII + cells and TCRcd + lymphocytes), iii) cytokine production (IFNA and IL12), and iv) phagocytosis were high and significantly different from zero. In addition, several innate ITs showed weak to moderate heritability, including proinflammatory cytokines (IL1B, IL8, TNF and IL6), MON, CD16 -CD2 + cells, CD16 + CD2cells, MHCII -CD172A + cells, MHCII + CD172Acells, CD16 -CD172A + cells and CD16 + CD172A + cells. Variation in acute phase proteins was moderately (CRP) to highly (HAPT) heritable. Among the four traits, which measured the total number (MON) or proportions (MHCII + CD172A + , CD16 + CD172A + and CD16 + MHCII + ) of monocytes, moderate to high h 2 , but not significantly different from zero, were estimated, except for CD16 + MHCII + cells. Other haematological traits (RBC, HT, RDW and PLT) gave high h 2 estimates, of which HT and PLT were significant.