Worth noting - incest doesn't cause problems all by itself. The problem is that siblings and first cousins are more likely to both inherit a genetic abnormality or disorder, and then pass that on to their kids. If a genetic abnormality or disorder isn't present then there's no genetic problem to be passed down.
Also, I'll keep mentioning this, the taboo against first cousin marriage in European cultures is very recent. Like 150-200 years recent, and even that's not consistent.
Worth noting - incest doesn't cause problems all by itself. The problem is that siblings and first cousins are more likely to both inherit a genetic abnormality or disorder, and then pass that on to their kids. If a genetic abnormality or disorder isn't present then there's no genetic problem to be passed down.
Also, I'll keep mentioning this, the taboo against first cousin marriage in European cultures is very recent. Like 150-200 years recent, and even that's not consistent.