What's the Name of That Book??? discussion

Okay so I read this book maybe about 8-9 years ago I believe? I remember the family living on an island away from most of civilization and so the brother and sister only grew up around each other. As a result, the brother began to have feelings for his sister eventually. I also remember a strange sailor visiting the island, who was a significantly older man, who got the girl sibling pregnant when she was very young I think around 13 or 14. The book has different flashbacks I remember from present day when the girl is older to when she was younger as well. I believe the mother narrates some as well. I think I remember a lighthouse being on the cover as well but I'm not 100% sure as searching this online has so far come up with nothing. If anyone has any possible ideas on what this book is, please let me know as I would love to read it again!

Was there any parenting going on? How did the older man get access to the young girl? What time period was it set in?

Also, did someone post a similar request to this recently? This sounds vaguely familiar but I could just be imagining that.

Maybe take a look at this list and see if anything looks familiar?
https://www.goodreads.com/list/show/2...
There's also several other lists specifically for castaway YA and Romance books etc but you didn't specify the genre you're looking for so I'm not linking all of them.

Yes the mother and father parented and loved their children. The man had access to the girl because he saw her and her brother talking and took interest in her. The brother left them alone for a while and that is when he probably coerced her into sex. The parents didn't find out about this until later I believe when she realized she was pregnant. I don't remember a specific time period, I think it was just assuredly present day!

Aerulan, thank you for the list but I don't believe it's on there. I tried looking at other lists earlier as well and couldn't find anything relevant. :/

The Lightkeeper's Daughter by Iain Lawrence? (Found searching online. The readers' descriptions sound just like yours!)

Alyssa, still looking or did you find this?