Dear Abby: My sister’s sons are adults now, but after 30 years abroad, they’re strangers to me

Dear Abby: My younger sister, who is divorced, has raised two sons who are now young adults but strangers to me. Sis and I have had an on-and-off relationship, but we love each other regardless of our differences. I married a Frenchman and have lived in France for the last 30 years. I haven’t seen Sis in 10 years. She has never been to France to visit me with her boys, although I have offered to pay for part of their expenses. We talk regularly, and I share photos of our family often. I haven’t seen a photo of her boys for 10 years. When I ask why, she laughs and says her boys dislike having their pictures taken. I find that difficult to accept. I find it hurtful and sad that she refuses to share any photos of my nephews with me. I’d like to go see her, but I’m afraid I won’t feel welcomed because of this. I feel she has isolated herself and her sons from the rest of her family. What should I do?