geopelia

There was a sad case some years ago, where two people who were not blood
relations were denied permission to marry because one was the adopted
brother of the other party. Legally they were considered brother and sister,
and it would be technically incest.
Perhaps this law needs looking at, with today's many blended families, where
children may not be blood relatives.

First cousins wishing to marry, (legal in some countries), should certainly
get medical advice and be tested for genetic diseases.
Geopelia