Do people (siblings) who get diagnosed with a chronic illness find it more bearable or worse to cope with because they have a partner in pain to talk to (a sibling with the same illness)?

I can't imagine how anyone copes with a chronic illness. And sometimes I wonder if it would be more bearable to have a sibling who also had the same problem. You could vent about the same problems or look at each other and be like "aaaah I feel so bad i'm sorry."