In September 1630, Alexander Blair, a tailor from Currie married his third wife, Catherine Windrahame, the daughter of his first wife’s half-brother. He was sentenced to be beheaded for incest. At the time cousins were no big deal.
In August 1626, Lanarkshire man, William Hamilton was put on trial for incest after he married the widow of his step-grandmother’s brother.
Worse yet, in June 1643, Janet Imrie lost her head for being the lover of two brothers, thus having caused them to have committed incest with each other.
The two brothers went unpunished.
If they’d been cousins, Janet probably would’ve been fine.