The DNA Detectives Facebook group has a fun calculator for those who've shared their autosomal raw data to one of the leading genealogy/genetic companies and now receive notifications of shared chromosomes with strangers. A few thousand new cousins, that is.
This is a handy guide unless your family suffers from endogamy.
I use"suffer" because cousins marrying cousins can only complicate your quest to determine kinship with one of your GGG-Grandparents' descendants.
Aye, there's the rub.