In this study, the effects of academic inbreeding on individual and institutional research productivity are examined to understand its impact as a recruitment policy. Over the past decade, in particular, there has been growing awareness of the problems posed by inbreeding in higher education. This study aims to expand on this awareness through an analysis of the prevalence of academic kinship in the Turkish higher education system, as well as the effects of inbreeding on the research productivity of academics and on their total research output. Unlike previous studies, the present study tests three distinct descriptions of inbreeding. The analyses in the study are performed on (1) the data records of 88,162 doctorate-holding faculty members’ nationally published articles and internationally published articles publications (Web of Science) from 203 Turkish universities;​ (2) their international citations;​ and (3) the projects they managed during the 2020–2021 academic year. Random effects estimator analyses were used the with multivariate negative binomial logit hurdle to account for institutional and individual differences. The findings indicate a high level of academic inbreeding in Turkish higher education. More specifically, the level was found to be 41%, which is one of the highest rates reported in the literature. Moreover, the findings suggest a negative impact of academic inbreeding on individual and institutional research productivity. In this respect, regardless of the field of study, inbred academics have lower number of national and internationally published articles, citations, and project management experiences than non-inbred researchers. In addition, it was found that the rate of academic inbreeding has a significant effect on universities’ research productivity. Given these results, it can be stated that academic inbreeding has a detrimental effect on higher education.