Since first-cousin marriages happen often enough among Iranians, as well as other Middle Easterners, the recent BBC Doha Debate, held in Qatar, on this topic may be relevant. Only a few decades ago, once in a while there would even be cases of young Iranian women being wed to their maternal uncles, although I wouldn’t know of the prevalence of that practice nowadays.
The focus of this debate is the genetic repercussions of close family marriages for the offspring and what, if anything, should be done about it. (Hence, it wouldn’t preclude you having childless ابتر affairs with your cousins.) Incidentally, Einstein married his maternal first cousin, who also happened to be his paternal second cousin, i.e. double jeopardy for the kids. Indeed, one of Einstein’s sons, Eduard, was schizophrenic. But Eduard was from his earlier wife, who was not related to Einstein.