I only know that when God breathed on MS Fallon one of the many, many beautiful things He gave her is freckels.
Beyond that it's not considerate or respectful to dig into her personal life- in my humble opinion.
Depending on whether it is indeed a tattoo or a birthmark, I disagree with the idea the Capn Davey is prying into her personal life by asking about it. It admittedly, may not be the most tactful question, but I'd imagine if it was something she didn't want us to see she wouldn't show us.