I don't mind lending money to parents and siblings, and they rarely ask if ever, but when they do, I help them no questions asked, and I don't even expect them to pay back.
I also don't mind lending to other relatives or close friends, but I expect them to pay back, whether it be with money or with favors when I'm in need. If I help them, but they always make up excuses when I need help, then they're not getting anything
Borrowing is a big fat NO for me, unless it's something incredibly serious like the risk of being evicted or something