>>113818716First cousins is where most cultures have drawn the line on what is considered incest, but it is drawn on both sides, Closer than that brings significant risks of genetic problems, while farther out has negligible risks. First cousins have about twice the risk of genetic defects in their children as two randomly selected members of the general population, meaning that if that risk concerns you, you should get genetic testing regardless of who you're interested in. However, first cousin marriages sustained over generations can lead to problems.
