Background: Consanguineous marriage is a relationship between biologically related individuals. Genetic factors have a role in gene environment interactions that takes the center stage. The evidence of oral disease (gingivitis and periodontitis) may depend on genetic syndromes, inherited diseases, familial studies etc. The present study aims at assessing dental plaque and gingival health condition in children of inbreeding parents compared with children of outbreeding parents among primary schools in Al-Qasem city/ Babylon governorate in Iraq. Materials and methods: this comparative study included three hundred ninety eight (398) students, 6-12 years old, from 4 primary schools; 199 children had their parents of inbreeding marriage with first level of inbreeding, and the other 199 children had parents of outbreeding marriage. Plaque status was assessed according to index of Silness and Loe (1964), gingival health status according to index of Loe and Silness (1963). Results: Children of inbreeding parents showed significantly higher plaque index and gingival index mean values than children of outbreeding parents. Mild gingivitis was found as the most prevalent type among both groups. A highly significant positive correlation was found between gingival and plaque indices. Conclusion: Inbreeding rates have an effect on oral health, as the children of outbreeding parents had significantly better oral hygiene and gingival health condition than children of inbreeding parents.