High Inbreeding
Although the Amish do not deliberately marry their cousins, there is a high risk of inbreeding in their families. Since Amish families are so small, they don’t have much of a choice when it comes to marrying another Amish person.
No Recruits
Another fascinating aspect of the Amish is that they reject evangelism. They have a tradition of excluding non-members and isolating themselves from the modern world. It’s no surprise, then, that the Amish refuse to recruit. Also, the most ardent supporters of the Amish are unable to join the church.